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<ul id="toc-Sources_of_systematic_error-sublist" class="vector-toc-list"> <li id="toc-Imperfect_calibration" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Imperfect_calibration"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1.1</span> <span>Imperfect calibration</span> </div> </a> <ul id="toc-Imperfect_calibration-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Quantity" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Quantity"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1.2</span> <span>Quantity</span> </div> </a> <ul id="toc-Quantity-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Drift" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Drift"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1.3</span> <span>Drift</span> </div> </a> <ul id="toc-Drift-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Sources_of_random_error" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Sources_of_random_error"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2</span> <span>Sources of random error</span> </div> </a> <ul id="toc-Sources_of_random_error-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Surveys" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Surveys"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Surveys</span> </div> </a> <ul id="toc-Surveys-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Effect_on_regression_analysis" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Effect_on_regression_analysis"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Effect on regression analysis</span> </div> </a> <ul id="toc-Effect_on_regression_analysis-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Further_reading" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Further_reading"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>Further reading</span> </div> </a> <ul id="toc-Further_reading-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span 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Available in 31 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-31" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">31 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%AE%D8%B7%D8%A3_%D8%A7%D9%84%D9%85%D9%84%D8%A7%D8%AD%D8%B8%D8%A9" title="خطأ الملاحظة – Arabic" lang="ar" hreflang="ar" data-title="خطأ الملاحظة" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-be mw-list-item"><a href="https://be.wikipedia.org/wiki/%D0%A5%D1%96%D0%B1%D0%BD%D0%B0%D1%81%D1%86%D1%8C" title="Хібнасць – Belarusian" lang="be" hreflang="be" data-title="Хібнасць" data-language-autonym="Беларуская" data-language-local-name="Belarusian" class="interlanguage-link-target"><span>Беларуская</span></a></li><li class="interlanguage-link interwiki-be-x-old mw-list-item"><a href="https://be-tarask.wikipedia.org/wiki/%D0%A5%D1%96%D0%B1%D0%BD%D0%B0%D1%81%D1%8C%D1%86%D1%8C" title="Хібнасьць – Belarusian (Taraškievica orthography)" lang="be-tarask" hreflang="be-tarask" data-title="Хібнасьць" data-language-autonym="Беларуская (тарашкевіца)" data-language-local-name="Belarusian (Taraškievica orthography)" class="interlanguage-link-target"><span>Беларуская (тарашкевіца)</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%93%D1%80%D0%B5%D1%88%D0%BA%D0%B8_%D0%BF%D1%80%D0%B8_%D0%B8%D0%B7%D0%BC%D0%B5%D1%80%D0%B2%D0%B0%D0%BD%D0%B5" title="Грешки при измерване – Bulgarian" lang="bg" hreflang="bg" data-title="Грешки при измерване" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Error_experimental" title="Error experimental – Catalan" lang="ca" hreflang="ca" data-title="Error experimental" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cv mw-list-item"><a href="https://cv.wikipedia.org/wiki/%D0%92%D0%B8%C3%A7%D0%B5%D0%B2_%D0%BF%C4%83%D1%80%C4%83%D0%BD%D0%B0%D0%B2%C4%95" title="Виçев пăрăнавĕ – Chuvash" lang="cv" hreflang="cv" data-title="Виçев пăрăнавĕ" data-language-autonym="Чӑвашла" data-language-local-name="Chuvash" class="interlanguage-link-target"><span>Чӑвашла</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Chyba_m%C4%9B%C5%99en%C3%AD" title="Chyba měření – Czech" lang="cs" hreflang="cs" data-title="Chyba měření" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Messabweichung" title="Messabweichung – German" lang="de" hreflang="de" data-title="Messabweichung" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/%CE%98%CE%B5%CF%89%CF%81%CE%AF%CE%B1_%CF%83%CF%86%CE%B1%CE%BB%CE%BC%CE%AC%CF%84%CF%89%CE%BD" title="Θεωρία σφαλμάτων – Greek" lang="el" hreflang="el" data-title="Θεωρία σφαλμάτων" data-language-autonym="Ελληνικά" data-language-local-name="Greek" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Error_de_medici%C3%B3n" title="Error de medición – Spanish" lang="es" hreflang="es" data-title="Error de medición" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/Behaketa-errore" title="Behaketa-errore – Basque" lang="eu" hreflang="eu" data-title="Behaketa-errore" data-language-autonym="Euskara" data-language-local-name="Basque" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%AE%D8%B7%D8%A7%DB%8C_%D9%85%D8%B4%D8%A7%D9%87%D8%AF%D9%87" title="خطای مشاهده – Persian" lang="fa" hreflang="fa" data-title="خطای مشاهده" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Erreur_de_mesure" title="Erreur de mesure – French" lang="fr" hreflang="fr" data-title="Erreur de mesure" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EA%B4%80%EC%B8%A1_%EC%98%A4%EC%B0%A8" title="관측 오차 – Korean" lang="ko" hreflang="ko" data-title="관측 오차" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Errore_di_misurazione" title="Errore di misurazione – Italian" lang="it" hreflang="it" data-title="Errore di misurazione" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%A9%D7%92%D7%99%D7%90%D7%AA_%D7%9E%D7%93%D7%99%D7%93%D7%94" title="שגיאת מדידה – Hebrew" lang="he" hreflang="he" data-title="שגיאת מדידה" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-lv mw-list-item"><a href="https://lv.wikipedia.org/wiki/M%C4%93r%C4%ABjuma_k%C4%BC%C5%ABda" title="Mērījuma kļūda – Latvian" lang="lv" hreflang="lv" data-title="Mērījuma kļūda" data-language-autonym="Latviešu" data-language-local-name="Latvian" class="interlanguage-link-target"><span>Latviešu</span></a></li><li class="interlanguage-link interwiki-lt mw-list-item"><a href="https://lt.wikipedia.org/wiki/Matavimo_paklaida" title="Matavimo paklaida – Lithuanian" lang="lt" hreflang="lt" data-title="Matavimo paklaida" data-language-autonym="Lietuvių" data-language-local-name="Lithuanian" class="interlanguage-link-target"><span>Lietuvių</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/Ralat_pemerhatian" title="Ralat pemerhatian – Malay" lang="ms" hreflang="ms" data-title="Ralat pemerhatian" data-language-autonym="Bahasa Melayu" data-language-local-name="Malay" class="interlanguage-link-target"><span>Bahasa Melayu</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/B%C5%82%C4%85d_pomiaru" title="Błąd pomiaru – Polish" lang="pl" hreflang="pl" data-title="Błąd pomiaru" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Erro_observacional" title="Erro observacional – Portuguese" lang="pt" hreflang="pt" data-title="Erro observacional" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/Eroare_de_m%C4%83surare" title="Eroare de măsurare – Romanian" lang="ro" hreflang="ro" data-title="Eroare de măsurare" data-language-autonym="Română" data-language-local-name="Romanian" class="interlanguage-link-target"><span>Română</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%9F%D0%BE%D0%B3%D1%80%D0%B5%D1%88%D0%BD%D0%BE%D1%81%D1%82%D1%8C_%D0%B8%D0%B7%D0%BC%D0%B5%D1%80%D0%B5%D0%BD%D0%B8%D1%8F" title="Погрешность измерения – Russian" lang="ru" hreflang="ru" data-title="Погрешность измерения" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Chyba_merania" title="Chyba merania – Slovak" lang="sk" hreflang="sk" data-title="Chyba merania" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/%D0%93%D1%80%D0%B5%D1%88%D0%BA%D0%B0_%D0%BC%D0%B5%D1%80%D0%B5%D1%9A%D0%B0" title="Грешка мерења – Serbian" lang="sr" hreflang="sr" data-title="Грешка мерења" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Mittausvirhe" title="Mittausvirhe – Finnish" lang="fi" hreflang="fi" data-title="Mittausvirhe" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/M%C3%A4tfel" title="Mätfel – Swedish" lang="sv" hreflang="sv" data-title="Mätfel" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/G%C3%B6zlem_hatas%C4%B1" title="Gözlem hatası – Turkish" lang="tr" hreflang="tr" data-title="Gözlem hatası" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%9F%D0%BE%D1%85%D0%B8%D0%B1%D0%BA%D0%B0_%D0%B2%D0%B8%D0%BC%D1%96%D1%80%D1%8E%D0%B2%D0%B0%D0%BD%D0%BD%D1%8F" title="Похибка вимірювання – Ukrainian" lang="uk" hreflang="uk" data-title="Похибка вимірювання" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/Sai_s%E1%BB%91" title="Sai số – Vietnamese" lang="vi" hreflang="vi" data-title="Sai số" data-language-autonym="Tiếng Việt" data-language-local-name="Vietnamese" class="interlanguage-link-target"><span>Tiếng Việt</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E6%B5%8B%E9%87%8F%E8%AF%AF%E5%B7%AE" 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<div class="mw-indicators"> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"><span class="mw-redirectedfrom">(Redirected from <a href="/w/index.php?title=Systematic_error&redirect=no" class="mw-redirect" title="Systematic error">Systematic error</a>)</span></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Difference between a measured value of a quantity and its true value</div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">"Systematic bias" redirects here. For the sociological and organizational phenomenon, see <a href="/wiki/Systemic_bias" title="Systemic bias">Systemic bias</a>.</div> <style data-mw-deduplicate="TemplateStyles:r1251242444">.mw-parser-output .ambox{border:1px solid #a2a9b1;border-left:10px solid #36c;background-color:#fbfbfb;box-sizing:border-box}.mw-parser-output .ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 0;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .ambox-speedy{border-left:10px solid #b32424;background-color:#fee7e6}.mw-parser-output .ambox-delete{border-left:10px solid #b32424}.mw-parser-output .ambox-content{border-left:10px solid #f28500}.mw-parser-output .ambox-style{border-left:10px solid #fc3}.mw-parser-output .ambox-move{border-left:10px solid #9932cc}.mw-parser-output .ambox-protection{border-left:10px solid #a2a9b1}.mw-parser-output .ambox .mbox-text{border:none;padding:0.25em 0.5em;width:100%}.mw-parser-output .ambox .mbox-image{border:none;padding:2px 0 2px 0.5em;text-align:center}.mw-parser-output .ambox .mbox-imageright{border:none;padding:2px 0.5em 2px 0;text-align:center}.mw-parser-output .ambox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ambox .mbox-image-div{width:52px}@media(min-width:720px){.mw-parser-output .ambox{margin:0 10%}}@media print{body.ns-0 .mw-parser-output .ambox{display:none!important}}</style><table class="box-More_citations_needed plainlinks metadata ambox ambox-content ambox-Refimprove" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><span typeof="mw:File"><a href="/wiki/File:Question_book-new.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/50px-Question_book-new.svg.png" decoding="async" width="50" height="39" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/75px-Question_book-new.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/100px-Question_book-new.svg.png 2x" data-file-width="512" data-file-height="399" /></a></span></div></td><td class="mbox-text"><div class="mbox-text-span">This article <b>needs additional citations for <a href="/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability">verification</a></b>.<span class="hide-when-compact"> Please help <a href="/wiki/Special:EditPage/Observational_error" title="Special:EditPage/Observational error">improve this article</a> by <a href="/wiki/Help:Referencing_for_beginners" title="Help:Referencing for beginners">adding citations to reliable sources</a>. Unsourced material may be challenged and removed.<br /><small><span class="plainlinks"><i>Find sources:</i> <a rel="nofollow" class="external text" href="https://www.google.com/search?as_eq=wikipedia&q=%22Observational+error%22">"Observational error"</a> – <a rel="nofollow" class="external text" href="https://www.google.com/search?tbm=nws&q=%22Observational+error%22+-wikipedia&tbs=ar:1">news</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.google.com/search?&q=%22Observational+error%22&tbs=bkt:s&tbm=bks">newspapers</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.google.com/search?tbs=bks:1&q=%22Observational+error%22+-wikipedia">books</a> <b>·</b> <a rel="nofollow" class="external text" href="https://scholar.google.com/scholar?q=%22Observational+error%22">scholar</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.jstor.org/action/doBasicSearch?Query=%22Observational+error%22&acc=on&wc=on">JSTOR</a></span></small></span> <span class="date-container"><i>(<span class="date">September 2016</span>)</i></span><span class="hide-when-compact"><i> (<small><a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a></small>)</i></span></div></td></tr></tbody></table> <p><b>Observational error</b> (or <b>measurement error</b>) is the difference between a <a href="/wiki/Measurement" title="Measurement">measured</a> value of a <a href="/wiki/Physical_quantity" title="Physical quantity">quantity</a> and its unknown <a href="/wiki/True_value" class="mw-redirect" title="True value">true value</a>.<sup id="cite_ref-Dodge_1-0" class="reference"><a href="#cite_note-Dodge-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> Such errors are inherent in the measurement process; for example lengths measured with a ruler calibrated in whole centimeters will have a measurement error of several millimeters. The error or uncertainty of a measurement can be estimated, and is specified with the measurement as, for example, 32.3 ± 0.5 cm. (A mistake or blunder in the measurement process will give an <em>incorrect</em> value, rather than one subject to known measurement error.) </p><p>Measurement errors can be divided into two components: <i><a href="/wiki/Statistical_randomness" title="Statistical randomness">random</a></i> and <i>systematic</i>.<sup id="cite_ref-Taylor_2-0" class="reference"><a href="#cite_note-Taylor-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> <b>Random errors</b> are <a href="/wiki/Error" title="Error">errors</a> in measurement that lead to measurable values being inconsistent when repeated measurements of a <a href="/wiki/Time-invariant" class="mw-redirect" title="Time-invariant">constant</a> attribute or <a href="/wiki/Physical_quantity" title="Physical quantity">quantity</a> are taken. <b>Systematic errors</b> are errors that are not determined by chance but are introduced by repeatable processes inherent to the <a href="/wiki/System" title="System">system</a>.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> Systematic error may also refer to an error with a non-zero <a href="/wiki/Mean" title="Mean">mean</a>, the <a href="/wiki/Causality" title="Causality">effect</a> of which is not reduced when <a href="/wiki/Observations" class="mw-redirect" title="Observations">observations</a> are <a href="/wiki/Averaged" class="mw-redirect" title="Averaged">averaged</a>.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (October 2019)">citation needed</span></a></i>]</sup> For example, length measurements with a ruler accurately calibrated in whole centimeters will be subject to random error; a ruler incorrectly calibrated will also produce systematic error. </p><p>Measurement errors can be summarized in terms of <a href="/wiki/Accuracy_and_precision" title="Accuracy and precision">accuracy and precision</a>. Measurement error should not be confused with <a href="/wiki/Measurement_uncertainty" title="Measurement uncertainty">measurement uncertainty</a>. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Science_and_experiments">Science and experiments</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Observational_error&action=edit&section=1" title="Edit section: Science and experiments"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>When either <a href="/wiki/Random_variable" title="Random variable">randomness</a> or uncertainty modeled by <a href="/wiki/Probability_theory" title="Probability theory">probability theory</a> is attributed to such errors, they are "errors" in the sense in which that term is used in <a href="/wiki/Statistics" title="Statistics">statistics</a>; see <a href="/wiki/Errors_and_residuals_in_statistics" class="mw-redirect" title="Errors and residuals in statistics">errors and residuals in statistics</a>. </p><p>Every time a measurement is repeated, slightly different results are obtained. The common <a href="/wiki/Statistical_model" title="Statistical model">statistical model</a> used is that the error has two additive parts: </p> <ol><li><b>Systematic error</b> which always occurs, with the same value, when we use the instrument in the same way and in the same case.</li> <li><b>Random error</b> which may vary from observation to another.</li></ol> <p>Systematic error is sometimes called <b>statistical bias</b>. It may often be reduced with standardized procedures. Part of the learning process in the various <a href="/wiki/Science" title="Science">sciences</a> is learning how to use standard instruments and protocols so as to minimize systematic error. </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Measurement_distribution_with_systematic_and_random_errors.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/8/84/Measurement_distribution_with_systematic_and_random_errors.svg/220px-Measurement_distribution_with_systematic_and_random_errors.svg.png" decoding="async" width="220" height="136" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/84/Measurement_distribution_with_systematic_and_random_errors.svg/330px-Measurement_distribution_with_systematic_and_random_errors.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/84/Measurement_distribution_with_systematic_and_random_errors.svg/440px-Measurement_distribution_with_systematic_and_random_errors.svg.png 2x" data-file-width="1072" data-file-height="665" /></a><figcaption>Distribution of measurements of known true value, with both constant systematic error and normally distributed random error.</figcaption></figure> <p>Random error (or <a href="/wiki/Random_variable" title="Random variable">random variation</a>) is due to factors that cannot or will not be controlled. One possible reason to forgo controlling for these random errors is that it may be too expensive to control them each time the experiment is conducted or the measurements are made. Other reasons may be that whatever we are trying to measure is changing in time (see <a href="/wiki/Dynamic_model" class="mw-redirect" title="Dynamic model">dynamic models</a>), or is fundamentally probabilistic (as is the case in quantum mechanics — see <a href="/wiki/Measurement_in_quantum_mechanics" title="Measurement in quantum mechanics">Measurement in quantum mechanics</a>). Random error often occurs when instruments are pushed to the extremes of their operating limits. For example, it is common for digital balances to exhibit random error in their least significant digit. Three measurements of a single object might read something like 0.9111g, 0.9110g, and 0.9112g. </p> <div class="mw-heading mw-heading2"><h2 id="Characterization">Characterization</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Observational_error&action=edit&section=2" title="Edit section: Characterization"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Accuracy_and_precision" title="Accuracy and precision">Accuracy and precision</a></div> <p>Measurement errors can be divided into two components: random error and systematic error.<sup id="cite_ref-Taylor_2-1" class="reference"><a href="#cite_note-Taylor-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p><b>Random error</b> is always present in a measurement. It is caused by inherently unpredictable fluctuations in the readings of a measurement apparatus or in the experimenter's interpretation of the instrumental reading. Random errors show up as different results for ostensibly the same repeated measurement. They can be estimated by comparing multiple measurements and reduced by averaging multiple measurements. </p><p><b>Systematic error</b> is predictable and typically constant or proportional to the true value. If the cause of the systematic error can be identified, then it usually can be eliminated. Systematic errors are caused by imperfect calibration of measurement instruments or imperfect methods of <a href="/wiki/Observation" title="Observation">observation</a>, or interference of the <a href="/wiki/Surroundings" title="Surroundings">environment</a> with the measurement process, and always affect the results of an <a href="/wiki/Experiment" title="Experiment">experiment</a> in a predictable direction. Incorrect zeroing of an instrument is an example of systematic error in instrumentation. </p><p>The Performance Test Standard PTC 19.1-2005 "Test Uncertainty", published by the <a href="/wiki/American_Society_of_Mechanical_Engineers" title="American Society of Mechanical Engineers">American Society of Mechanical Engineers</a> (ASME), discusses systematic and random errors in considerable detail. In fact, it conceptualizes its basic uncertainty categories in these terms. </p><p>Random error can be caused by unpredictable fluctuations in the readings of a measurement apparatus, or in the experimenter's interpretation of the instrumental reading; these fluctuations may be in part due to interference of the environment with the measurement process. The concept of random error is closely related to the concept of <a href="/wiki/Accuracy_and_precision" title="Accuracy and precision">precision</a>. The higher the precision of a measurement instrument, the smaller the variability (<a href="/wiki/Standard_deviation" title="Standard deviation">standard deviation</a>) of the fluctuations in its readings. </p> <div class="mw-heading mw-heading2"><h2 id="Sources">Sources</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Observational_error&action=edit&section=3" title="Edit section: Sources"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="Sources_of_systematic_error">Sources of systematic error<span class="anchor" id="Systematic"></span></h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Observational_error&action=edit&section=4" title="Edit section: Sources of systematic error"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading4"><h4 id="Imperfect_calibration">Imperfect calibration</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Observational_error&action=edit&section=5" title="Edit section: Imperfect calibration"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Sources of systematic error may be imperfect calibration of measurement instruments (zero error), changes in the <a href="/wiki/Biophysical_environment" class="mw-redirect" title="Biophysical environment">environment</a> which interfere with the measurement process and sometimes imperfect methods of <a href="/wiki/Observation" title="Observation">observation</a> can be either zero error or percentage error. If you consider an experimenter taking a reading of the time period of a pendulum swinging past a <a href="/wiki/Fiducial_marker" title="Fiducial marker">fiducial marker</a>: If their stop-watch or timer starts with 1 second on the clock then all of their results will be off by 1 second (zero error). If the experimenter repeats this experiment twenty times (starting at 1 second each time), then there will be a <a href="/wiki/Percentage_error" class="mw-redirect" title="Percentage error">percentage error</a> in the calculated average of their results; the final result will be slightly larger than the true period. </p><p><a href="/wiki/Distance" title="Distance">Distance</a> measured by <a href="/wiki/Radar" title="Radar">radar</a> will be systematically overestimated if the slight slowing down of the waves in air is not accounted for. Incorrect zeroing of an instrument is an example of systematic error in instrumentation. </p><p>Systematic errors may also be present in the result of an <a href="/wiki/Computational_mechanics" title="Computational mechanics">estimate</a> based upon a <a href="/wiki/Mathematical_model" title="Mathematical model">mathematical model</a> or <a href="/wiki/Physical_law" class="mw-redirect" title="Physical law">physical law</a>. For instance, the estimated <a href="/wiki/Oscillation_frequency" class="mw-redirect" title="Oscillation frequency">oscillation frequency</a> of a <a href="/wiki/Pendulum" title="Pendulum">pendulum</a> will be systematically in error if slight movement of the support is not accounted for. </p> <div class="mw-heading mw-heading4"><h4 id="Quantity">Quantity</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Observational_error&action=edit&section=6" title="Edit section: Quantity"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Systematic errors can be either constant, or related (e.g. proportional or a percentage) to the actual value of the measured quantity, or even to the value of a different quantity (the reading of a <a href="/wiki/Ruler" title="Ruler">ruler</a> can be affected by environmental temperature). When it is constant, it is simply due to incorrect zeroing of the instrument. When it is not constant, it can change its sign. For instance, if a thermometer is affected by a proportional systematic error equal to 2% of the actual temperature, and the actual temperature is 200°, 0°, or −100°, the measured temperature will be 204° (systematic error = +4°), 0° (null systematic error) or −102° (systematic error = −2°), respectively. Thus the temperature will be overestimated when it will be above zero and underestimated when it will be below zero. </p> <div class="mw-heading mw-heading4"><h4 id="Drift">Drift</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Observational_error&action=edit&section=7" title="Edit section: Drift"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Systematic errors which change during an experiment (<a href="/wiki/Stochastic_drift" title="Stochastic drift">drift</a>) are easier to detect. Measurements indicate trends with time rather than varying randomly about a <a href="/wiki/Mean" title="Mean">mean</a>. Drift is evident if a measurement of a <a href="/wiki/Constant_(mathematics)" title="Constant (mathematics)">constant</a> quantity is repeated several times and the measurements drift one way during the experiment. If the next measurement is higher than the previous measurement as may occur if an instrument becomes warmer during the experiment then the measured quantity is variable and it is possible to detect a drift by checking the zero reading during the experiment as well as at the start of the experiment (indeed, the <a href="/wiki/Vernier_scale" title="Vernier scale">zero reading</a> is a measurement of a constant quantity). If the zero reading is consistently above or below zero, a systematic error is present. If this cannot be eliminated, potentially by resetting the instrument immediately before the experiment then it needs to be allowed by subtracting its (possibly time-varying) value from the readings, and by taking it into account while assessing the accuracy of the measurement. </p><p>If no pattern in a series of repeated measurements is evident, the presence of fixed systematic errors can only be found if the measurements are checked, either by measuring a known quantity or by comparing the readings with readings made using a different apparatus, known to be more accurate. For example, if you think of the timing of a pendulum using an accurate <a href="/wiki/Stopwatch" title="Stopwatch">stopwatch</a> several times you are given readings randomly distributed about the mean. Hopings systematic error is present if the stopwatch is checked against the '<a href="/wiki/Speaking_clock" title="Speaking clock">speaking clock</a>' of the telephone system and found to be running slow or fast. Clearly, the pendulum timings need to be corrected according to how fast or slow the stopwatch was found to be running. </p><p>Measuring instruments such as <a href="/wiki/Ammeter" title="Ammeter">ammeters</a> and <a href="/wiki/Voltmeter" title="Voltmeter">voltmeters</a> need to be checked periodically against known standards. </p><p>Systematic errors can also be detected by measuring already known quantities. For example, a <a href="/wiki/Spectrometer" title="Spectrometer">spectrometer</a> fitted with a <a href="/wiki/Diffraction_grating" title="Diffraction grating">diffraction grating</a> may be checked by using it to measure the <a href="/wiki/Wavelength" title="Wavelength">wavelength</a> of the D-lines of the <a href="/wiki/Sodium" title="Sodium">sodium</a> <a href="/wiki/Electromagnetic_spectrum" title="Electromagnetic spectrum">electromagnetic spectrum</a> which are at 600 nm and 589.6 nm. The measurements may be used to determine the number of lines per millimetre of the diffraction grating, which can then be used to measure the wavelength of any other spectral line. </p><p>Constant systematic errors are very difficult to deal with as their effects are only observable if they can be removed. Such errors cannot be removed by repeating measurements or averaging large numbers of results. A common method to remove systematic error is through <a href="/wiki/Calibration" title="Calibration">calibration</a> of the measurement instrument. </p> <div class="mw-heading mw-heading3"><h3 id="Sources_of_random_error">Sources of random error<span class="anchor" id="Random"></span></h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Observational_error&action=edit&section=8" title="Edit section: Sources of random error"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The random or stochastic error in a measurement is the error that is random from one measurement to the next. Stochastic errors tend to be <a href="/wiki/Normal_distribution" title="Normal distribution">normally distributed</a> when the stochastic error is the sum of many independent random errors because of the <a href="/wiki/Central_limit_theorem" title="Central limit theorem">central limit theorem</a>. Stochastic errors added to a regression equation account for the variation in <i>Y</i> that cannot be explained by the included <i>X</i>s. </p> <div class="mw-heading mw-heading2"><h2 id="Surveys">Surveys</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Observational_error&action=edit&section=9" title="Edit section: Surveys"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The term "observational error" is also sometimes used to refer to response errors and some other types of <a href="/wiki/Non-sampling_error" title="Non-sampling error">non-sampling error</a>.<sup id="cite_ref-Dodge_1-1" class="reference"><a href="#cite_note-Dodge-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> In survey-type situations, these errors can be mistakes in the collection of data, including both the incorrect recording of a response and the correct recording of a respondent's inaccurate response. These sources of non-sampling error are discussed in Salant and Dillman (1994) and Bland and Altman (1996).<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p><p>These errors can be random or systematic. Random errors are caused by unintended mistakes by respondents, interviewers and/or coders. Systematic error can occur if there is a systematic reaction of the respondents to the method used to formulate the survey question. Thus, the exact formulation of a survey question is crucial, since it affects the level of measurement error.<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> Different tools are available for the researchers to help them decide about this exact formulation of their questions, for instance estimating the quality of a question using <a href="/wiki/Multitrait-multimethod_matrix" title="Multitrait-multimethod matrix">MTMM experiments</a>. This information about the quality can also be used in order to <a href="/wiki/Correction_for_attenuation" class="mw-redirect" title="Correction for attenuation">correct for measurement error</a>.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Effect_on_regression_analysis">Effect on regression analysis</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Observational_error&action=edit&section=10" title="Edit section: Effect on regression analysis"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>If the <a href="/wiki/Dependent_variable" class="mw-redirect" title="Dependent variable">dependent variable</a> in a regression is measured with error, regression analysis and associated hypothesis testing are unaffected, except that the <a href="/wiki/Coefficient_of_determination" title="Coefficient of determination">R<sup>2</sup></a> will be lower than it would be with perfect measurement. </p><p>However, if one or more <a href="/wiki/Independent_variable" class="mw-redirect" title="Independent variable">independent variables</a> is measured with error, then the regression coefficients and standard <a href="/wiki/Hypothesis_test" class="mw-redirect" title="Hypothesis test">hypothesis tests</a> are invalid.<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> This is known as <a href="/wiki/Regression_dilution" title="Regression dilution">attenuation bias</a>.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Observational_error&action=edit&section=11" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1184024115">.mw-parser-output .div-col{margin-top:0.3em;column-width:30em}.mw-parser-output .div-col-small{font-size:90%}.mw-parser-output .div-col-rules{column-rule:1px solid #aaa}.mw-parser-output .div-col dl,.mw-parser-output .div-col ol,.mw-parser-output .div-col ul{margin-top:0}.mw-parser-output .div-col li,.mw-parser-output .div-col dd{page-break-inside:avoid;break-inside:avoid-column}</style><div class="div-col" style="column-width: 20em;"> <ul><li><a href="/wiki/Bias_(statistics)" title="Bias (statistics)">Bias (statistics)</a></li> <li><a href="/wiki/Cognitive_bias" title="Cognitive bias">Cognitive bias</a></li> <li><a href="/wiki/Correction_for_attenuation" class="mw-redirect" title="Correction for attenuation">Correction for measurement error</a> (for Pearson correlations)</li> <li><a href="/wiki/Error" title="Error">Error</a></li> <li><a href="/wiki/Errors_and_residuals_in_statistics" class="mw-redirect" title="Errors and residuals in statistics">Errors and residuals in statistics</a></li> <li><a href="/wiki/Errors-in-variables_models" title="Errors-in-variables models">Errors-in-variables models</a></li> <li><a href="/wiki/Instrument_error" title="Instrument error">Instrument error</a></li> <li><a href="/wiki/Measurement_uncertainty" title="Measurement uncertainty">Measurement uncertainty</a></li> <li><a href="/wiki/Metrology" title="Metrology">Metrology</a></li> <li><a href="/wiki/Outlier" title="Outlier">Outlier</a></li> <li><a href="/wiki/Propagation_of_uncertainty" title="Propagation of uncertainty">Propagation of uncertainty</a></li> <li><a href="/wiki/Regression_dilution" title="Regression dilution">Regression dilution</a></li> <li><a href="/wiki/Replication_(statistics)" title="Replication (statistics)">Replication (statistics)</a></li> <li><a href="/wiki/Statistical_theory" title="Statistical theory">Statistical theory</a></li> <li><a href="/wiki/Systemic_bias" title="Systemic bias">Systemic bias</a></li> <li><a href="/wiki/Test_method" title="Test method">Test method</a></li></ul> </div> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Observational_error&action=edit&section=12" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist"> <div class="mw-references-wrap"><ol class="references"> <li id="cite_note-Dodge-1"><span class="mw-cite-backlink">^ <a href="#cite_ref-Dodge_1-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Dodge_1-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">Dodge, Y. (2003) <i>The Oxford Dictionary of Statistical Terms</i>, OUP. <style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-19-920613-1" title="Special:BookSources/978-0-19-920613-1">978-0-19-920613-1</a></span> </li> <li id="cite_note-Taylor-2"><span class="mw-cite-backlink">^ <a href="#cite_ref-Taylor_2-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Taylor_2-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFJohn_Robert_Taylor1999" class="citation book cs1">John Robert Taylor (1999). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=giFQcZub80oC&pg=PA94"><i>An Introduction to Error Analysis: The Study of Uncertainties in Physical Measurements</i></a>. University Science Books. p. 94, §4.1. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-935702-75-0" title="Special:BookSources/978-0-935702-75-0"><bdi>978-0-935702-75-0</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=An+Introduction+to+Error+Analysis%3A+The+Study+of+Uncertainties+in+Physical+Measurements&rft.pages=94%2C+%C2%A74.1&rft.pub=University+Science+Books&rft.date=1999&rft.isbn=978-0-935702-75-0&rft.au=John+Robert+Taylor&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DgiFQcZub80oC%26pg%3DPA94&rfr_id=info%3Asid%2Fen.wikipedia.org%3AObservational+error" class="Z3988"></span></span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.merriam-webster.com/dictionary/systematic%20error">"Systematic error"</a>. <i>Merriam-webster.com</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2016-09-10</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Merriam-webster.com&rft.atitle=Systematic+error&rft_id=http%3A%2F%2Fwww.merriam-webster.com%2Fdictionary%2Fsystematic%2520error&rfr_id=info%3Asid%2Fen.wikipedia.org%3AObservational+error" class="Z3988"></span></span> </li> <li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFSalantDillman1994" class="citation book cs1">Salant, P.; Dillman, D. A. (1994). <span class="id-lock-registration" title="Free registration required"><a rel="nofollow" class="external text" href="https://archive.org/details/howtoconductyour00sala"><i>How to conduct your survey</i></a></span>. New York: John Wiley & Sons. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-471-01273-4" title="Special:BookSources/0-471-01273-4"><bdi>0-471-01273-4</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=How+to+conduct+your+survey&rft.place=New+York&rft.pub=John+Wiley+%26+Sons&rft.date=1994&rft.isbn=0-471-01273-4&rft.aulast=Salant&rft.aufirst=P.&rft.au=Dillman%2C+D.+A.&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fhowtoconductyour00sala&rfr_id=info%3Asid%2Fen.wikipedia.org%3AObservational+error" class="Z3988"></span></span> </li> <li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBlandAltman1996" class="citation journal cs1">Bland, J. Martin; Altman, Douglas G. (1996). <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2352101">"Statistics Notes: Measurement Error"</a>. <i>BMJ</i>. <b>313</b> (7059): 744. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1136%2Fbmj.313.7059.744">10.1136/bmj.313.7059.744</a>. <a href="/wiki/PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2352101">2352101</a></span>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/8819450">8819450</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=BMJ&rft.atitle=Statistics+Notes%3A+Measurement+Error&rft.volume=313&rft.issue=7059&rft.pages=744&rft.date=1996&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC2352101%23id-name%3DPMC&rft_id=info%3Apmid%2F8819450&rft_id=info%3Adoi%2F10.1136%2Fbmj.313.7059.744&rft.aulast=Bland&rft.aufirst=J.+Martin&rft.au=Altman%2C+Douglas+G.&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC2352101&rfr_id=info%3Asid%2Fen.wikipedia.org%3AObservational+error" class="Z3988"></span></span> </li> <li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFSarisGallhofer2014" class="citation book cs1">Saris, W. E.; Gallhofer, I. N. (2014). <i>Design, Evaluation and Analysis of Questionnaires for Survey Research</i> (Second ed.). Hoboken: Wiley. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-118-63461-5" title="Special:BookSources/978-1-118-63461-5"><bdi>978-1-118-63461-5</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Design%2C+Evaluation+and+Analysis+of+Questionnaires+for+Survey+Research&rft.place=Hoboken&rft.edition=Second&rft.pub=Wiley&rft.date=2014&rft.isbn=978-1-118-63461-5&rft.aulast=Saris&rft.aufirst=W.+E.&rft.au=Gallhofer%2C+I.+N.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AObservational+error" class="Z3988"></span></span> </li> <li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text">DeCastellarnau, A. and Saris, W. E. (2014). A simple procedure to correct for measurement errors in survey research. European Social Survey Education Net (ESS EduNet). Available at: <a rel="nofollow" class="external text" href="http://essedunet.nsd.uib.no/cms/topics/measurement/">http://essedunet.nsd.uib.no/cms/topics/measurement</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20190915033804/http://essedunet.nsd.uib.no/cms/topics/measurement">Archived</a> 2019-09-15 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a></span> </li> <li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFSarisRevilla2015" class="citation journal cs1">Saris, W. E.; Revilla, M. (2015). <a rel="nofollow" class="external text" href="http://repositori.upf.edu/bitstream/10230/28341/1/RECSM-WP-031-Correction%20for%20measurement%20errors%20in%20survey%20research.pdf">"Correction for measurement errors in survey research: necessary and possible"</a> <span class="cs1-format">(PDF)</span>. <i>Social Indicators Research</i>. <b>127</b> (3): 1005–1020. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1007%2Fs11205-015-1002-x">10.1007/s11205-015-1002-x</a>. <a href="/wiki/Hdl_(identifier)" class="mw-redirect" title="Hdl (identifier)">hdl</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://hdl.handle.net/10230%2F28341">10230/28341</a></span>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:146550566">146550566</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Social+Indicators+Research&rft.atitle=Correction+for+measurement+errors+in+survey+research%3A+necessary+and+possible&rft.volume=127&rft.issue=3&rft.pages=1005-1020&rft.date=2015&rft_id=info%3Ahdl%2F10230%2F28341&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A146550566%23id-name%3DS2CID&rft_id=info%3Adoi%2F10.1007%2Fs11205-015-1002-x&rft.aulast=Saris&rft.aufirst=W.+E.&rft.au=Revilla%2C+M.&rft_id=http%3A%2F%2Frepositori.upf.edu%2Fbitstream%2F10230%2F28341%2F1%2FRECSM-WP-031-Correction%2520for%2520measurement%2520errors%2520in%2520survey%2520research.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AObservational+error" class="Z3988"></span></span> </li> <li id="cite_note-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-9">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFHayashi2000" class="citation book cs1">Hayashi, Fumio (2000). <i>Econometrics</i>. Princeton University Press. p. 187. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-691-01018-2" title="Special:BookSources/978-0-691-01018-2"><bdi>978-0-691-01018-2</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Econometrics&rft.pages=187&rft.pub=Princeton+University+Press&rft.date=2000&rft.isbn=978-0-691-01018-2&rft.aulast=Hayashi&rft.aufirst=Fumio&rfr_id=info%3Asid%2Fen.wikipedia.org%3AObservational+error" class="Z3988"></span></span> </li> <li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFAngristPischke2015" class="citation book cs1">Angrist, Joshua David; Pischke, Jörn-Steffen (2015). <a rel="nofollow" class="external text" href="https://www.worldcat.org/oclc/877846199"><i>Mastering 'metrics : the path from cause to effect</i></a>. Princeton, New Jersey: Princeton University Press. p. 221. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-691-15283-7" title="Special:BookSources/978-0-691-15283-7"><bdi>978-0-691-15283-7</bdi></a>. <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/877846199">877846199</a>. <q>The bias generated by this sort of measurement error in regressors is called attenuation bias.</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Mastering+%27metrics+%3A+the+path+from+cause+to+effect&rft.place=Princeton%2C+New+Jersey&rft.pages=221&rft.pub=Princeton+University+Press&rft.date=2015&rft_id=info%3Aoclcnum%2F877846199&rft.isbn=978-0-691-15283-7&rft.aulast=Angrist&rft.aufirst=Joshua+David&rft.au=Pischke%2C+J%C3%B6rn-Steffen&rft_id=https%3A%2F%2Fwww.worldcat.org%2Foclc%2F877846199&rfr_id=info%3Asid%2Fen.wikipedia.org%3AObservational+error" class="Z3988"></span></span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Observational_error&action=edit&section=13" title="Edit section: Further reading"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFCochran1968" class="citation journal cs1">Cochran, W. G. (1968). "Errors of Measurement in Statistics". <i><a href="/wiki/Technometrics" title="Technometrics">Technometrics</a></i>. <b>10</b> (4): 637–666. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.2307%2F1267450">10.2307/1267450</a>. <a href="/wiki/JSTOR_(identifier)" class="mw-redirect" title="JSTOR (identifier)">JSTOR</a> <a rel="nofollow" class="external text" href="https://www.jstor.org/stable/1267450">1267450</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:120645541">120645541</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Technometrics&rft.atitle=Errors+of+Measurement+in+Statistics&rft.volume=10&rft.issue=4&rft.pages=637-666&rft.date=1968&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A120645541%23id-name%3DS2CID&rft_id=https%3A%2F%2Fwww.jstor.org%2Fstable%2F1267450%23id-name%3DJSTOR&rft_id=info%3Adoi%2F10.2307%2F1267450&rft.aulast=Cochran&rft.aufirst=W.+G.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AObservational+error" class="Z3988"></span></li></ul> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output 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href="/wiki/Template_talk:Biases" title="Template talk:Biases"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Biases" title="Special:EditPage/Template:Biases"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Biases" style="font-size:114%;margin:0 4em"><a href="/wiki/Bias" title="Bias">Biases</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;"><a href="/wiki/Cognitive_bias" title="Cognitive bias">Cognitive biases</a></div></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Acquiescence_bias" title="Acquiescence bias">Acquiescence</a></li> <li><a href="/wiki/Ambiguity_effect" title="Ambiguity effect">Ambiguity</a></li> <li><a href="/wiki/Affinity_bias" title="Affinity bias">Affinity</a></li> <li><a href="/wiki/Anchoring_(cognitive_bias)" class="mw-redirect" title="Anchoring (cognitive bias)">Anchoring</a></li> <li><a href="/wiki/Attentional_bias" title="Attentional bias">Attentional</a></li> <li><a href="/wiki/Attribution_bias" title="Attribution bias">Attribution</a> <ul><li><a href="/wiki/Actor%E2%80%93observer_asymmetry" title="Actor–observer asymmetry">Actor–observer</a></li> <li><a href="/wiki/Fundamental_attribution_error" title="Fundamental attribution error">Correspondence</a></li></ul></li> <li><a href="/wiki/Authority_bias" title="Authority bias">Authority</a></li> <li><a href="/wiki/Automation_bias" title="Automation bias">Automation</a></li> <li><a href="/wiki/Availability_heuristic" title="Availability heuristic">Availability</a> <ul><li><a href="/wiki/Mean_world_syndrome" title="Mean world syndrome">Mean world</a></li></ul></li> <li><a href="/wiki/Belief_bias" title="Belief bias">Belief</a></li> <li><a href="/wiki/Bias_blind_spot" title="Bias blind spot">Blind spot</a></li> <li><a href="/wiki/Choice-supportive_bias" title="Choice-supportive bias">Choice-supportive</a></li> <li><a href="/wiki/Escalation_of_commitment" title="Escalation of commitment">Commitment</a></li> <li><a href="/wiki/Confirmation_bias" title="Confirmation bias">Confirmation</a> <ul><li><a href="/wiki/Selective_perception" title="Selective perception">Selective perception</a></li></ul></li> <li><a href="/wiki/Compassion_fade" title="Compassion fade">Compassion fade</a></li> <li><a href="/wiki/Congruence_bias" title="Congruence bias">Congruence</a></li> <li><a href="/wiki/Cultural_bias" title="Cultural bias">Cultural</a></li> <li><a href="/wiki/Declinism" title="Declinism">Declinism</a></li> <li><a href="/wiki/Distinction_bias" title="Distinction bias">Distinction</a></li> <li><a href="/wiki/Dunning%E2%80%93Kruger_effect" title="Dunning–Kruger effect">Dunning–Kruger</a></li> <li><a href="/wiki/Egocentric_bias" title="Egocentric bias">Egocentric</a> <ul><li><a href="/wiki/Curse_of_knowledge" title="Curse of knowledge">Curse of knowledge</a></li></ul></li> <li><a href="/wiki/Emotional_bias" title="Emotional bias">Emotional</a></li> <li><a href="/wiki/Extrinsic_incentives_bias" title="Extrinsic incentives bias">Extrinsic incentives</a></li> <li><a href="/wiki/Fading_affect_bias" title="Fading affect bias">Fading affect</a></li> <li><a href="/wiki/Framing_effect_(psychology)" title="Framing effect (psychology)">Framing</a></li> <li><a href="/wiki/Frequency_illusion" title="Frequency illusion">Frequency</a></li> <li><a href="/wiki/Frog_pond_effect" title="Frog pond effect">Frog pond effect</a></li> <li><a href="/wiki/Halo_effect" title="Halo effect">Halo effect</a></li> <li><a href="/wiki/Hindsight_bias" title="Hindsight bias">Hindsight</a></li> <li><a href="/wiki/Horn_effect" title="Horn effect">Horn effect</a></li> <li><a href="/wiki/Hostile_attribution_bias" title="Hostile attribution bias">Hostile attribution</a></li> <li><a href="/wiki/Impact_bias" title="Impact bias">Impact</a></li> <li><a href="/wiki/Implicit_stereotype" title="Implicit stereotype">Implicit</a></li> <li><a href="/wiki/In-group_favoritism" title="In-group favoritism">In-group</a></li> <li><a href="/wiki/Intentionality_bias" title="Intentionality bias">Intentionality</a></li> <li><a href="/wiki/Illusion_of_transparency" title="Illusion of transparency">Illusion of transparency</a></li> <li><a href="/wiki/Mean_world_syndrome" title="Mean world syndrome">Mean world syndrome</a></li> <li><a href="/wiki/Mere-exposure_effect" title="Mere-exposure effect">Mere-exposure effect</a></li> <li><a href="/wiki/Narrative_bias" title="Narrative bias">Narrative</a></li> <li><a href="/wiki/Negativity_bias" title="Negativity bias">Negativity</a></li> <li><a href="/wiki/Normalcy_bias" title="Normalcy bias">Normalcy</a></li> <li><a href="/wiki/Omission_bias" title="Omission bias">Omission</a></li> <li><a href="/wiki/Optimism_bias" title="Optimism bias">Optimism</a></li> <li><a href="/wiki/Out-group_homogeneity" title="Out-group homogeneity">Out-group homogeneity</a></li> <li><a href="/wiki/Outcome_bias" title="Outcome bias">Outcome</a></li> <li><a href="/wiki/Overton_window" title="Overton window">Overton window</a></li> <li><a href="/wiki/Precision_bias" title="Precision bias">Precision</a></li> <li><a href="/wiki/Present_bias" title="Present bias">Present</a></li> <li><a href="/wiki/Pro-innovation_bias" title="Pro-innovation bias">Pro-innovation</a></li> <li><a href="/wiki/Proximity_bias" title="Proximity bias">Proximity</a></li> <li><a href="/wiki/Response_bias" title="Response bias">Response</a></li> <li><a href="/wiki/Restraint_bias" title="Restraint bias">Restraint</a></li> <li><a href="/wiki/Self-serving_bias" title="Self-serving bias">Self-serving</a></li> <li><a href="/wiki/Social_comparison_bias" title="Social comparison bias">Social comparison</a></li> <li><a href="/wiki/Social_influence_bias" title="Social influence bias">Social influence bias</a></li> <li><a href="/wiki/Spotlight_effect" title="Spotlight effect">Spotlight</a></li> <li><a href="/wiki/Status_quo_bias" title="Status quo bias">Status quo</a></li> <li><a href="/wiki/Attribute_substitution" title="Attribute substitution">Substitution</a></li> <li><a href="/wiki/Time-saving_bias" title="Time-saving bias">Time-saving</a></li> <li><a href="/wiki/Trait_ascription_bias" title="Trait ascription bias">Trait ascription</a></li> <li><a href="/wiki/Turkey_illusion" title="Turkey illusion">Turkey illusion</a></li> <li><a href="/wiki/Von_Restorff_effect" title="Von Restorff effect">von Restorff effect</a></li> <li><a href="/wiki/Zero-risk_bias" title="Zero-risk bias">Zero-risk</a></li> <li><a href="/wiki/Cognitive_bias_in_animals" title="Cognitive bias in animals">In animals</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Bias_(statistics)" title="Bias (statistics)">Statistical biases</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Bias_of_an_estimator" title="Bias of an estimator">Estimator</a></li> <li><a href="/wiki/Forecast_bias" title="Forecast bias">Forecast</a></li> <li><a href="/wiki/Healthy_user_bias" title="Healthy user bias">Healthy user</a></li> <li><a href="/wiki/Information_bias_(epidemiology)" title="Information bias (epidemiology)">Information</a> <ul><li><a href="/wiki/Information_bias_(psychology)" title="Information bias (psychology)">Psychological</a></li></ul></li> <li><a href="/wiki/Lead_time_bias" title="Lead time bias">Lead time</a></li> <li><a href="/wiki/Length_time_bias" title="Length time bias">Length time</a></li> <li><a href="/wiki/Participation_bias" title="Participation bias">Non-response</a></li> <li><a href="/wiki/Observer_bias" title="Observer bias">Observer</a></li> <li><a href="/wiki/Omitted-variable_bias" title="Omitted-variable bias">Omitted-variable</a></li> <li><a href="/wiki/Participation_bias" title="Participation bias">Participation</a></li> <li><a href="/wiki/Recall_bias" title="Recall bias">Recall</a></li> <li><a href="/wiki/Sampling_bias" title="Sampling bias">Sampling</a></li> <li><a href="/wiki/Selection_bias" title="Selection bias">Selection</a></li> <li><a href="/wiki/Self-selection_bias" title="Self-selection bias">Self-selection</a></li> <li><a href="/wiki/Social-desirability_bias" title="Social-desirability bias">Social desirability</a></li> <li><a href="/wiki/Spectrum_bias" title="Spectrum bias">Spectrum</a></li> <li><a href="/wiki/Survivorship_bias" title="Survivorship bias">Survivorship</a></li> <li><a href="/wiki/Systematic_error" class="mw-redirect" title="Systematic error">Systematic error</a></li> <li><a href="/wiki/Systemic_bias" title="Systemic bias">Systemic</a></li> <li><a href="/wiki/Verification_bias" title="Verification bias">Verification</a></li> <li><a href="/wiki/Wet_bias" title="Wet bias">Wet</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other biases</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Academic_bias" title="Academic bias">Academic</a></li> <li><a href="/wiki/Basking_in_reflected_glory" title="Basking in reflected glory">Basking in reflected glory</a></li> <li><i><a href="/wiki/D%C3%A9formation_professionnelle" title="Déformation professionnelle">Déformation professionnelle</a></i></li> <li><a href="/wiki/Funding_bias" title="Funding bias">Funding</a></li> <li><a href="/wiki/FUTON_bias" class="mw-redirect" title="FUTON bias">FUTON</a></li> <li><a href="/wiki/Inductive_bias" title="Inductive bias">Inductive</a></li> <li><a href="/wiki/Infrastructure_bias" title="Infrastructure bias">Infrastructure</a></li> <li><a href="/wiki/Inherent_bias" title="Inherent bias">Inherent</a></li> <li><a href="/wiki/Bias_in_education" class="mw-redirect" title="Bias in education">In education</a></li> <li><a href="/wiki/Liking_gap" title="Liking gap">Liking gap</a></li> <li><a href="/wiki/Media_bias" title="Media bias">Media</a> <ul><li><a href="/wiki/False_balance" title="False balance">False balance</a></li> <li><a href="/wiki/United_States_news_media_and_the_Vietnam_War" title="United States news media and the Vietnam War">Vietnam War</a></li> <li><a href="/wiki/Media_of_Norway" class="mw-redirect" title="Media of Norway">Norway</a></li> <li><a href="/wiki/Media_bias_in_South_Asia" title="Media bias in South Asia">South Asia</a></li> <li><a href="/wiki/Media_of_Sweden" class="mw-redirect" title="Media of Sweden">Sweden</a></li> <li><a href="/wiki/Media_bias_in_the_United_States" title="Media bias in the United States">United States</a></li> <li><a href="/wiki/Media_coverage_of_the_Arab%E2%80%93Israeli_conflict" class="mw-redirect" title="Media coverage of the Arab–Israeli conflict">Arab–Israeli conflict</a></li> <li><a href="/wiki/Media_portrayal_of_the_Ukrainian_crisis" class="mw-redirect" title="Media portrayal of the Ukrainian crisis">Ukraine</a></li></ul></li> <li><a href="/wiki/Net_bias" title="Net bias">Net</a></li> <li><a href="/wiki/Political_bias" title="Political bias">Political bias</a></li> <li><a href="/wiki/Publication_bias" title="Publication bias">Publication</a></li> <li><a href="/wiki/Reporting_bias" title="Reporting bias">Reporting</a></li> <li><a href="/wiki/White_hat_bias" title="White hat bias">White hat</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Bias reduction</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Cognitive_bias_mitigation" title="Cognitive bias mitigation">Cognitive bias mitigation</a></li> <li><a href="/wiki/Debiasing" title="Debiasing">Debiasing</a></li> <li><a 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