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role="button" id="ca-edit" href="/w/index.php?title=Observational_study&action=edit" data-event-name="menu.edit" data-mw="interface" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet edit-page menu__item--page-actions-edit"> <span class="minerva-icon minerva-icon--edit"></span> <span>Edit</span> </a> </li> </ul> </nav>  <div id="mw-content-subtitle"></div> </div> <div id="bodyContent" class="content"> <div id="mw-content-text" class="mw-body-content"><script>function mfTempOpenSection(id){var block=document.getElementById("mf-section-"+id);block.className+=" open-block";block.previousSibling.className+=" open-block";}</script><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><section class="mf-section-0" id="mf-section-0"> <p>In fields such as <a href="/wiki/Epidemiology" title="Epidemiology">epidemiology</a>, <a href="/wiki/Social_science" title="Social science">social sciences</a>, <a href="/wiki/Psychology" title="Psychology">psychology</a> and <a href="/wiki/Statistics" title="Statistics">statistics</a>, an <b>observational study</b> draws inferences from a <a href="/wiki/Sample_(statistics)" class="mw-redirect" title="Sample (statistics)">sample</a> to a <a href="/wiki/Statistical_population" title="Statistical population">population</a> where the <a href="/wiki/Dependent_and_independent_variables" title="Dependent and independent variables">independent variable</a> is not under the <a href="/wiki/Scientific_control" title="Scientific control">control</a> of the researcher because of ethical concerns or logistical constraints. One common observational study is about the possible effect of a treatment on subjects, where the assignment of subjects into a treated group versus a <a href="/wiki/Control_group" class="mw-redirect" title="Control group">control group</a> is outside the control of the investigator.<sup id="cite_ref-urlObservational_study_1-0" class="reference"><a href="#cite_note-urlObservational_study-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> This is in contrast with <a href="/wiki/Experiment" title="Experiment">experiments</a>, such as <a href="/wiki/Randomized_controlled_trial" title="Randomized controlled trial">randomized controlled trials</a>, where each subject is <a href="/wiki/Random_assignment" title="Random assignment">randomly assigned</a> to a treated group or a control group. Observational studies, for lacking an assignment mechanism, naturally present difficulties for inferential analysis. </p><figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Blankett,_Antropoloogiline_vaatlusleht,_vorm_nr._4,_1961.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c9/Blankett%2C_Antropoloogiline_vaatlusleht%2C_vorm_nr._4%2C_1961.jpg/220px-Blankett%2C_Antropoloogiline_vaatlusleht%2C_vorm_nr._4%2C_1961.jpg" decoding="async" width="220" height="151" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c9/Blankett%2C_Antropoloogiline_vaatlusleht%2C_vorm_nr._4%2C_1961.jpg/330px-Blankett%2C_Antropoloogiline_vaatlusleht%2C_vorm_nr._4%2C_1961.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c9/Blankett%2C_Antropoloogiline_vaatlusleht%2C_vorm_nr._4%2C_1961.jpg/440px-Blankett%2C_Antropoloogiline_vaatlusleht%2C_vorm_nr._4%2C_1961.jpg 2x" data-file-width="2446" data-file-height="1680"></a><figcaption>Anthropological survey paper from 1961 by <a href="/w/index.php?title=Juhan_Aul&action=edit&redlink=1" class="new" title="Juhan Aul (page does not exist)">Juhan Aul</a> (<a href="https://et.wikipedia.org/wiki/Juhan_Aul" class="extiw" title="et:Juhan Aul">et</a>) from <a href="/wiki/University_of_Tartu" title="University of Tartu">University of Tartu</a> who measured about 50 000 people</figcaption></figure> <div id="toc" class="toc" role="navigation" aria-labelledby="mw-toc-heading"><input type="checkbox" role="button" id="toctogglecheckbox" class="toctogglecheckbox" style="display:none"><div class="toctitle" lang="en" dir="ltr"><h2 id="mw-toc-heading">Contents</h2><span class="toctogglespan"><label class="toctogglelabel" for="toctogglecheckbox"></label></span></div> <ul> <li class="toclevel-1 tocsection-1"><a href="#Motivation"><span class="tocnumber">1</span> <span class="toctext">Motivation</span></a></li> <li class="toclevel-1 tocsection-2"><a href="#Types"><span class="tocnumber">2</span> <span class="toctext">Types</span></a></li> <li class="toclevel-1 tocsection-3"><a href="#Degree_of_usefulness_and_reliability"><span class="tocnumber">3</span> <span class="toctext">Degree of usefulness and reliability</span></a></li> <li class="toclevel-1 tocsection-4"><a href="#Bias_and_compensating_methods"><span class="tocnumber">4</span> <span class="toctext">Bias and compensating methods</span></a> <ul> <li class="toclevel-2 tocsection-5"><a href="#Matching_techniques_bias"><span class="tocnumber">4.1</span> <span class="toctext">Matching techniques bias</span></a></li> <li class="toclevel-2 tocsection-6"><a href="#Multiple_comparison_bias"><span class="tocnumber">4.2</span> <span class="toctext">Multiple comparison bias</span></a></li> <li class="toclevel-2 tocsection-7"><a href="#Omitted_variable_bias"><span class="tocnumber">4.3</span> <span class="toctext">Omitted variable bias</span></a></li> <li class="toclevel-2 tocsection-8"><a href="#Selection_bias"><span class="tocnumber">4.4</span> <span class="toctext">Selection bias</span></a></li> </ul> </li> <li class="toclevel-1 tocsection-9"><a href="#Quality"><span class="tocnumber">5</span> <span class="toctext">Quality</span></a></li> <li class="toclevel-1 tocsection-10"><a href="#See_also"><span class="tocnumber">6</span> <span class="toctext">See also</span></a></li> <li class="toclevel-1 tocsection-11"><a href="#References"><span class="tocnumber">7</span> <span class="toctext">References</span></a></li> <li class="toclevel-1 tocsection-12"><a href="#Further_reading"><span class="tocnumber">8</span> <span class="toctext">Further reading</span></a></li> </ul> </div> </section><div class="mw-heading mw-heading2 section-heading" onclick="mfTempOpenSection(1)"><span class="indicator mf-icon mf-icon-expand mf-icon--small"></span><h2 id="Motivation">Motivation</h2><span class="mw-editsection"> <a role="button" href="/w/index.php?title=Observational_study&action=edit&section=1" title="Edit section: Motivation" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> <span class="minerva-icon minerva-icon--edit"></span> <span>edit</span> </a> </span> </div><section class="mf-section-1 collapsible-block" id="mf-section-1"> <p>The independent variable may be beyond the control of the investigator for a variety of reasons: </p> <ul><li>A randomized experiment would violate <a href="/wiki/Ethics" title="Ethics">ethical</a> standards. Suppose one wanted to investigate the <a href="/wiki/Abortion_%E2%80%93_breast_cancer_hypothesis" class="mw-redirect" title="Abortion – breast cancer hypothesis">abortion – breast cancer hypothesis</a>, which postulates a causal link between induced abortion and the incidence of breast cancer. In a hypothetical controlled experiment, one would start with a large subject pool of pregnant women and divide them randomly into a treatment group (receiving induced abortions) and a control group (not receiving abortions), and then conduct regular cancer screenings for women from both groups. Needless to say, such an experiment would run counter to common ethical principles. (It would also suffer from various confounds and sources of bias, e.g. it would be impossible to conduct it as a <a href="/wiki/Blind_experiment" class="mw-redirect" title="Blind experiment">blind experiment</a>.) The published studies investigating the abortion–breast cancer hypothesis generally start with a group of women who already have received abortions. Membership in this "treated" group is not controlled by the investigator: the group is formed after the "treatment" has been assigned.<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. (May 2010)">citation needed</span></a></i>]</sup></li> <li>The investigator may simply lack the requisite influence. Suppose a scientist wants to study the public health effects of a community-wide ban on smoking in public indoor areas. In a controlled experiment, the investigator would randomly pick a set of communities to be in the treatment group. However, it is typically up to each community and/or its legislature to enact a <a href="/wiki/Smoking_ban" title="Smoking ban">smoking ban</a>. The investigator can be expected to lack the political power to cause precisely those communities in the randomly selected treatment group to pass a smoking ban. In an observational study, the investigator would typically start with a treatment group consisting of those communities where a smoking ban is already in effect.<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. (May 2010)">citation needed</span></a></i>]</sup></li> <li>A randomized experiment may be impractical. Suppose a researcher wants to study the suspected link between a certain medication and a very rare group of symptoms arising as a side effect. Setting aside any ethical considerations, a randomized experiment would be impractical because of the rarity of the effect. There may not be a subject pool large enough for the symptoms to be observed in at least one treated subject. An observational study would typically start with a group of symptomatic subjects and work backwards to find those who were given the medication and later developed the symptoms. Thus a subset of the treated group was determined based on the presence of symptoms, instead of by random assignment.<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. (May 2010)">citation needed</span></a></i>]</sup></li> <li>Many <a href="/wiki/Randomized_controlled_trial" title="Randomized controlled trial">randomized controlled trials</a> are not broadly representative of real-world patients and this may limit their <a href="/wiki/External_validity" title="External validity">external validity</a>. Patients who are eligible for inclusion in a randomized controlled trial are usually younger, more likely to be male, healthier and more likely to be treated according to recommendations from guidelines.<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> If and when the intervention is later added to routine-care, a large portion of the patients who will receive it may be old with many concomitant diseases and drug-therapies, altho</li></ul> </section><div class="mw-heading mw-heading2 section-heading" onclick="mfTempOpenSection(2)"><span class="indicator mf-icon mf-icon-expand mf-icon--small"></span><h2 id="Types">Types</h2><span class="mw-editsection"> <a role="button" href="/w/index.php?title=Observational_study&action=edit&section=2" title="Edit section: Types" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> <span class="minerva-icon minerva-icon--edit"></span> <span>edit</span> </a> </span> </div><section class="mf-section-2 collapsible-block" id="mf-section-2"> <ul><li><a href="/wiki/Case-control_study" class="mw-redirect" title="Case-control study">Case-control study</a>: study originally developed in epidemiology, in which two existing groups differing in outcome are identified and compared on the basis of some supposed causal attribute.</li> <li><a href="/wiki/Cross-sectional_study" title="Cross-sectional study">Cross-sectional study</a>: involves data collection from a population, or a representative subset, at one specific point in time.</li> <li><a href="/wiki/Longitudinal_study" title="Longitudinal study">Longitudinal study</a>: correlational research <a href="/wiki/Study_of_global_communication" title="Study of global communication">study</a> that involves repeated observations of the same variables over long periods of time. <a href="/wiki/Cohort_study" title="Cohort study">Cohort study</a> and <a href="/wiki/Panel_analysis" title="Panel analysis">Panel study</a> are particular forms of longitudinal study.</li></ul> </section><div class="mw-heading mw-heading2 section-heading" onclick="mfTempOpenSection(3)"><span class="indicator mf-icon mf-icon-expand mf-icon--small"></span><h2 id="Degree_of_usefulness_and_reliability">Degree of usefulness and reliability</h2><span class="mw-editsection"> <a role="button" href="/w/index.php?title=Observational_study&action=edit&section=3" title="Edit section: Degree of usefulness and reliability" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> <span class="minerva-icon minerva-icon--edit"></span> <span>edit</span> </a> </span> </div><section class="mf-section-3 collapsible-block" id="mf-section-3"> <p>"Although observational studies cannot be used to make definitive statements of fact about the "safety, efficacy, or effectiveness" of a practice, they can:<sup id="cite_ref-Nahin_4-0" class="reference"><a href="#cite_note-Nahin-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p> <ol><li>provide information on 'real world' use and practice;</li> <li>detect signals about the benefits and risks of...[the] use [of practices] in the general population;</li> <li>help formulate hypotheses to be tested in subsequent experiments;</li> <li>provide part of the community-level data needed to design more informative pragmatic clinical trials; and</li> <li>inform clinical practice."<sup id="cite_ref-Nahin_4-1" class="reference"><a href="#cite_note-Nahin-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup></li></ol> </section><div class="mw-heading mw-heading2 section-heading" onclick="mfTempOpenSection(4)"><span class="indicator mf-icon mf-icon-expand mf-icon--small"></span><h2 id="Bias_and_compensating_methods">Bias and compensating methods</h2><span class="mw-editsection"> <a role="button" href="/w/index.php?title=Observational_study&action=edit&section=4" title="Edit section: Bias and compensating methods" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> <span class="minerva-icon minerva-icon--edit"></span> <span>edit</span> </a> </span> </div><section class="mf-section-4 collapsible-block" id="mf-section-4"> <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-text"><div class="mbox-text-span">This section <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_study" title="Special:EditPage/Observational study">improve this article</a> by <a href="/wiki/Help:Referencing_for_beginners" title="Help:Referencing for beginners">adding citations to reliable sources</a> in this section. 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+study%22">"Observational study"</a> – <a rel="nofollow" class="external text" href="https://www.google.com/search?tbm=nws&q=%22Observational+study%22+-wikipedia&tbs=ar:1">news</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.google.com/search?&q=%22Observational+study%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+study%22+-wikipedia">books</a> <b>·</b> <a rel="nofollow" class="external text" href="https://scholar.google.com/scholar?q=%22Observational+study%22">scholar</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.jstor.org/action/doBasicSearch?Query=%22Observational+study%22&acc=on&wc=on">JSTOR</a></span></small></span> <span class="date-container"><i>(<span class="date">August 2021</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>In all of those cases, if a randomized experiment cannot be carried out, the alternative line of investigation suffers from the problem that the decision of which subjects receive the treatment is not entirely random and thus is a potential source of <a href="/wiki/Bias" title="Bias">bias</a>. A major challenge in conducting observational studies is to draw inferences that are acceptably free from influences by overt biases, as well as to assess the influence of potential hidden biases. The following are a non-exhaustive set of problems especially common in observational studies. </p> <div class="mw-heading mw-heading3"><h3 id="Matching_techniques_bias">Matching techniques bias</h3><span class="mw-editsection"> <a role="button" href="/w/index.php?title=Observational_study&action=edit&section=5" title="Edit section: Matching techniques bias" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> <span class="minerva-icon minerva-icon--edit"></span> <span>edit</span> </a> </span> </div> <p>In lieu of experimental control, <a href="/wiki/Multivariate_statistics" title="Multivariate statistics">multivariate statistical</a> techniques allow the approximation of experimental control with statistical control by using matching methods. Matching methods account for the influences of observed factors that might influence a cause-and-effect relationship. In <a href="/wiki/Healthcare" class="mw-redirect" title="Healthcare">healthcare</a> and the <a href="/wiki/Social_science" title="Social science">social sciences</a>, investigators may use <a href="/wiki/Matching_(statistics)" title="Matching (statistics)">matching</a> to compare units that nonrandomly received the treatment and control. One common approach is to use <a href="/wiki/Propensity_score_matching" title="Propensity score matching">propensity score matching</a> in order to reduce <a href="/wiki/Confounding" title="Confounding">confounding</a>,<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> although this has recently come under criticism for exacerbating the very problems it seeks to solve.<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> </p> <div class="mw-heading mw-heading3"><h3 id="Multiple_comparison_bias">Multiple comparison bias</h3><span class="mw-editsection"> <a role="button" href="/w/index.php?title=Observational_study&action=edit&section=6" title="Edit section: Multiple comparison bias" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> <span class="minerva-icon minerva-icon--edit"></span> <span>edit</span> </a> </span> </div> <p><a href="/wiki/Multiple_comparisons_problem" title="Multiple comparisons problem">Multiple comparison bias</a> can occur when several hypotheses are tested at the same time. As the number of recorded factors increases, the likelihood increases that at least one of the recorded factors will be highly correlated with the data output simply by chance.<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> </p> <div class="mw-heading mw-heading3"><h3 id="Omitted_variable_bias">Omitted variable bias</h3><span class="mw-editsection"> <a role="button" href="/w/index.php?title=Observational_study&action=edit&section=7" title="Edit section: Omitted variable bias" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> <span class="minerva-icon minerva-icon--edit"></span> <span>edit</span> </a> </span> </div> <p>An observer of an uncontrolled experiment (or process) records potential factors and the data output: the goal is to determine the effects of the factors. Sometimes the recorded factors may not be directly causing the differences in the output. There may be more important factors which were not recorded but are, in fact, causal. Also, recorded or unrecorded factors may be correlated which may yield incorrect conclusions.<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-heading3"><h3 id="Selection_bias">Selection bias</h3><span class="mw-editsection"> <a role="button" href="/w/index.php?title=Observational_study&action=edit&section=8" title="Edit section: Selection bias" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> <span class="minerva-icon minerva-icon--edit"></span> <span>edit</span> </a> </span> </div> <p>Another difficulty with observational studies is that researchers may themselves be biased in their observational skills. This would allow for researchers to (either consciously or unconsciously) seek out the information they're looking for while conducting their research. For example, researchers may exaggerate the effect of one variable, or downplay the effect of another: researchers may even select in subjects that fit their conclusions. This selection bias can happen at any stage of the research process. This introduces bias into the data where certain variables are systematically incorrectly measured.<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> </p> </section><div class="mw-heading mw-heading2 section-heading" onclick="mfTempOpenSection(5)"><span class="indicator mf-icon mf-icon-expand mf-icon--small"></span><h2 id="Quality">Quality</h2><span class="mw-editsection"> <a role="button" href="/w/index.php?title=Observational_study&action=edit&section=9" title="Edit section: Quality" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> <span class="minerva-icon minerva-icon--edit"></span> <span>edit</span> </a> </span> </div><section class="mf-section-5 collapsible-block" id="mf-section-5"> <p>A 2014 (updated in 2024) <a href="/wiki/Cochrane_Collaboration" class="mw-redirect" title="Cochrane Collaboration">Cochrane</a> review concluded that observational studies produce results similar to those conducted as <a href="/wiki/Randomized_controlled_trial" title="Randomized controlled trial">randomized controlled trials</a>.<sup id="cite_ref-:0_10-0" class="reference"><a href="#cite_note-:0-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> The review reported little evidence for significant effect differences between observational studies and randomized controlled trials, regardless of design.<sup id="cite_ref-:0_10-1" class="reference"><a href="#cite_note-:0-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> Differences need to be evaluated by looking at population, comparator, heterogeneity, and outcomes.<sup id="cite_ref-:0_10-2" class="reference"><a href="#cite_note-:0-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> </p> </section><div class="mw-heading mw-heading2 section-heading" onclick="mfTempOpenSection(6)"><span class="indicator mf-icon mf-icon-expand mf-icon--small"></span><h2 id="See_also">See also</h2><span class="mw-editsection"> <a role="button" href="/w/index.php?title=Observational_study&action=edit&section=10" title="Edit section: See also" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> <span class="minerva-icon minerva-icon--edit"></span> <span>edit</span> </a> </span> </div><section class="mf-section-6 collapsible-block" id="mf-section-6"> <ul><li><a href="/wiki/Correlation_does_not_imply_causation" title="Correlation does not imply causation">Correlation does not imply causation</a></li> <li><a href="/wiki/Observation" title="Observation">Observation</a></li> <li><a href="/wiki/Difference-in-differences" class="mw-redirect" title="Difference-in-differences">Difference-in-differences</a></li> <li><a href="/wiki/Randomized_controlled_trial" title="Randomized controlled trial">Randomized controlled trial</a> (RCT)</li> <li><a href="/wiki/Blinded_experiment" title="Blinded experiment">Blinded experiment</a></li> <li><a href="/wiki/Scientific_method" title="Scientific method">Scientific method</a></li></ul> </section><div class="mw-heading mw-heading2 section-heading" onclick="mfTempOpenSection(7)"><span class="indicator mf-icon mf-icon-expand mf-icon--small"></span><h2 id="References">References</h2><span class="mw-editsection"> <a role="button" href="/w/index.php?title=Observational_study&action=edit&section=11" title="Edit section: References" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> <span class="minerva-icon minerva-icon--edit"></span> <span>edit</span> </a> </span> </div><section class="mf-section-7 collapsible-block" id="mf-section-7"> <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-urlObservational_study-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-urlObservational_study_1-0">^</a></b></span> <span class="reference-text"><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><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20160427111413/http://www.medicine.ox.ac.uk/bandolier/booth/glossary/observ.html">"Observational study"</a>. Archived from <a rel="nofollow" class="external text" href="http://www.medicine.ox.ac.uk:80/bandolier/booth/glossary/observ.html">the original</a> on 2016-04-27<span class="reference-accessdate">. Retrieved <span class="nowrap">2008-06-25</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Observational+study&rft_id=http%3A%2F%2Fwww.medicine.ox.ac.uk%3A80%2Fbandolier%2Fbooth%2Fglossary%2Fobserv.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AObservational+study" class="Z3988"></span></span> </li> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFPorta2008" class="citation book cs1">Porta M, ed. (2008). <i>A Dictionary of Epidemiology</i> (5th ed.). New York: Oxford University Press. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9780195314496" title="Special:BookSources/9780195314496"><bdi>9780195314496</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=A+Dictionary+of+Epidemiology&rft.place=New+York&rft.edition=5th&rft.pub=Oxford+University+Press&rft.date=2008&rft.isbn=9780195314496&rfr_id=info%3Asid%2Fen.wikipedia.org%3AObservational+study" 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 id="CITEREFKennedy-MartinCurtisFariesRobinson2015" class="citation journal cs1">Kennedy-Martin T, Curtis S, Faries D, Robinson S, Johnston J (November 2015). <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4632358">"A literature review on the representativeness of randomized controlled trial samples and implications for the external validity of trial results"</a>. <i>Trials</i>. <b>16</b> (1): 495. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1186%2Fs13063-015-1023-4">10.1186/s13063-015-1023-4</a></span>. <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/PMC4632358">4632358</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/26530985">26530985</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Trials&rft.atitle=A+literature+review+on+the+representativeness+of+randomized+controlled+trial+samples+and+implications+for+the+external+validity+of+trial+results&rft.volume=16&rft.issue=1&rft.pages=495&rft.date=2015-11&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC4632358%23id-name%3DPMC&rft_id=info%3Apmid%2F26530985&rft_id=info%3Adoi%2F10.1186%2Fs13063-015-1023-4&rft.aulast=Kennedy-Martin&rft.aufirst=T&rft.au=Curtis%2C+S&rft.au=Faries%2C+D&rft.au=Robinson%2C+S&rft.au=Johnston%2C+J&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC4632358&rfr_id=info%3Asid%2Fen.wikipedia.org%3AObservational+study" class="Z3988"></span></span> </li> <li id="cite_note-Nahin-4"><span class="mw-cite-backlink">^ <a href="#cite_ref-Nahin_4-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Nahin_4-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">"Although observational studies cannot provide definitive evidence of safety, efficacy, or effectiveness, they can: 1) provide information on "real world" use and practice; 2) detect signals about the benefits and risks of complementary therapies use in the general population; 3) help formulate hypotheses to be tested in subsequent experiments; 4) provide part of the community-level data needed to design more informative pragmatic clinical trials; and 5) inform clinical practice." <a rel="nofollow" class="external text" href="http://nccih.nih.gov/research/blog/observational-secondary">"Observational Studies and Secondary Data Analyses To Assess Outcomes in Complementary and Integrative Health Care."</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20190929034831/https://nccih.nih.gov/research/blog/observational-secondary">Archived</a> 2019-09-29 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a> Richard Nahin, Ph.D., M.P.H., Senior Advisor for Scientific Coordination and Outreach, <a href="/wiki/National_Center_for_Complementary_and_Integrative_Health" title="National Center for Complementary and Integrative Health">National Center for Complementary and Integrative Health</a>, June 25, 2012</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">Rosenbaum, Paul R. 2009. <i>Design of Observational Studies</i>. New York: Springer.</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="CITEREFKingNielsen2019" class="citation journal cs1">King, Gary; Nielsen, Richard (2019-05-07). "Why Propensity Scores Should Not Be Used for Matching". <i>Political Analysis</i>. <b>27</b> (4): 435–454. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1017%2Fpan.2019.11">10.1017/pan.2019.11</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/1721.1%2F128459">1721.1/128459</a></span>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1047-1987">1047-1987</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:53585283">53585283</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Political+Analysis&rft.atitle=Why+Propensity+Scores+Should+Not+Be+Used+for+Matching&rft.volume=27&rft.issue=4&rft.pages=435-454&rft.date=2019-05-07&rft_id=info%3Ahdl%2F1721.1%2F128459&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A53585283%23id-name%3DS2CID&rft.issn=1047-1987&rft_id=info%3Adoi%2F10.1017%2Fpan.2019.11&rft.aulast=King&rft.aufirst=Gary&rft.au=Nielsen%2C+Richard&rfr_id=info%3Asid%2Fen.wikipedia.org%3AObservational+study" class="Z3988"></span> | <a rel="nofollow" class="external text" href="https://gking.harvard.edu/files/gking/files/psnot.pdf">link to the full article</a> (from the author's homepage</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"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBenjamini2010" class="citation journal cs1">Benjamini, Yoav (2010). <a rel="nofollow" class="external text" href="https://onlinelibrary.wiley.com/doi/10.1002/bimj.200900299">"Simultaneous and selective inference: Current successes and future challenges"</a>. <i>Biometrical Journal</i>. <b>52</b> (6): 708–721. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1002%2Fbimj.200900299">10.1002/bimj.200900299</a>. <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/21154895">21154895</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:8806192">8806192</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Biometrical+Journal&rft.atitle=Simultaneous+and+selective+inference%3A+Current+successes+and+future+challenges&rft.volume=52&rft.issue=6&rft.pages=708-721&rft.date=2010&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A8806192%23id-name%3DS2CID&rft_id=info%3Apmid%2F21154895&rft_id=info%3Adoi%2F10.1002%2Fbimj.200900299&rft.aulast=Benjamini&rft.aufirst=Yoav&rft_id=https%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fbimj.200900299&rfr_id=info%3Asid%2Fen.wikipedia.org%3AObservational+study" class="Z3988"></span></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 class="citation web cs1"><a rel="nofollow" class="external text" href="http://www3.wabash.edu/econometrics/EconometricsBook/chap18.htm">"Introductory Econometrics Chapter 18: Omitted Variable Bias"</a>. <i>www3.wabash.edu</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2022-07-16</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www3.wabash.edu&rft.atitle=Introductory+Econometrics+Chapter+18%3A+Omitted+Variable+Bias&rft_id=http%3A%2F%2Fwww3.wabash.edu%2Feconometrics%2FEconometricsBook%2Fchap18.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3AObservational+study" 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="CITEREFHammerdu_PrelBlettner2009" class="citation journal cs1">Hammer, Gaël P; du Prel, Jean-Baptist; Blettner, Maria (2009-10-01). <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2780010">"Avoiding Bias in Observational Studies"</a>. <i>Deutsches Ärzteblatt International</i>. <b>106</b> (41): 664–668. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.3238%2Farztebl.2009.0664">10.3238/arztebl.2009.0664</a>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1866-0452">1866-0452</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/PMC2780010">2780010</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/19946431">19946431</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Deutsches+%C3%84rzteblatt+International&rft.atitle=Avoiding+Bias+in+Observational+Studies&rft.volume=106&rft.issue=41&rft.pages=664-668&rft.date=2009-10-01&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC2780010%23id-name%3DPMC&rft.issn=1866-0452&rft_id=info%3Apmid%2F19946431&rft_id=info%3Adoi%2F10.3238%2Farztebl.2009.0664&rft.aulast=Hammer&rft.aufirst=Ga%C3%ABl+P&rft.au=du+Prel%2C+Jean-Baptist&rft.au=Blettner%2C+Maria&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC2780010&rfr_id=info%3Asid%2Fen.wikipedia.org%3AObservational+study" class="Z3988"></span></span> </li> <li id="cite_note-:0-10"><span class="mw-cite-backlink">^ <a href="#cite_ref-:0_10-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:0_10-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-:0_10-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFToewsAnglemyerNyirendaAlsaid2024" class="citation journal cs1">Toews, Ingrid; Anglemyer, Andrew; Nyirenda, John Lz; Alsaid, Dima; Balduzzi, Sara; Grummich, Kathrin; Schwingshackl, Lukas; Bero, Lisa (2024-01-04). "Healthcare outcomes assessed with observational study designs compared with those assessed in randomized trials: a meta-epidemiological study". <i>The Cochrane Database of Systematic Reviews</i>. <b>1</b> (1): MR000034. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1002%2F14651858.MR000034.pub3">10.1002/14651858.MR000034.pub3</a>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1469-493X">1469-493X</a>. <a href="/wiki/PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> 10765475. <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/38174786">38174786</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+Cochrane+Database+of+Systematic+Reviews&rft.atitle=Healthcare+outcomes+assessed+with+observational+study+designs+compared+with+those+assessed+in+randomized+trials%3A+a+meta-epidemiological+study&rft.volume=1&rft.issue=1&rft.pages=MR000034&rft.date=2024-01-04&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC10765475%23id-name%3DPMC&rft.issn=1469-493X&rft_id=info%3Apmid%2F38174786&rft_id=info%3Adoi%2F10.1002%2F14651858.MR000034.pub3&rft.aulast=Toews&rft.aufirst=Ingrid&rft.au=Anglemyer%2C+Andrew&rft.au=Nyirenda%2C+John+Lz&rft.au=Alsaid%2C+Dima&rft.au=Balduzzi%2C+Sara&rft.au=Grummich%2C+Kathrin&rft.au=Schwingshackl%2C+Lukas&rft.au=Bero%2C+Lisa&rfr_id=info%3Asid%2Fen.wikipedia.org%3AObservational+study" class="Z3988"></span></span> </li> </ol></div></div> </section><div class="mw-heading mw-heading2 section-heading" onclick="mfTempOpenSection(8)"><span class="indicator mf-icon mf-icon-expand mf-icon--small"></span><h2 id="Further_reading">Further reading</h2><span class="mw-editsection"> <a role="button" href="/w/index.php?title=Observational_study&action=edit&section=12" title="Edit section: Further reading" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> <span class="minerva-icon minerva-icon--edit"></span> <span>edit</span> </a> </span> </div><section class="mf-section-8 collapsible-block" id="mf-section-8"> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFRosenbaum2002" class="citation book cs1">Rosenbaum PR (2002). <i>Observational Studies</i> (2nd ed.). New York: Springer-Verlag. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0387989676" title="Special:BookSources/0387989676"><bdi>0387989676</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Observational+Studies&rft.place=New+York&rft.edition=2nd&rft.pub=Springer-Verlag&rft.date=2002&rft.isbn=0387989676&rft.aulast=Rosenbaum&rft.aufirst=Paul+R.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AObservational+study" class="Z3988"></span></li> <li><a rel="nofollow" class="external text" href="http://www.itl.nist.gov/div898/handbook/">"NIST/SEMATECH Handbook on Engineering Statistics"</a> at <a href="/wiki/National_Institute_of_Standards_and_Technology" title="National Institute of Standards and Technology">NIST</a></li></ul> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output 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<h4>Languages</h4> <section> <ul id="p-variants" class="minerva-languages"></ul> <ul class="minerva-languages"><li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%AF%D8%B1%D8%A7%D8%B3%D8%A9_%D8%A8%D8%A7%D9%84%D9%85%D9%84%D8%A7%D8%AD%D8%B8%D8%A9" title="دراسة بالملاحظة – Arabic" lang="ar" hreflang="ar" data-title="دراسة بالملاحظة" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-ast mw-list-item"><a href="https://ast.wikipedia.org/wiki/Estudiu_observacional" title="Estudiu observacional – Asturian" lang="ast" hreflang="ast" data-title="Estudiu observacional" data-language-autonym="Asturianu" data-language-local-name="Asturian" class="interlanguage-link-target"><span>Asturianu</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Beobachtungsstudie" title="Beobachtungsstudie – German" lang="de" hreflang="de" data-title="Beobachtungsstudie" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Estudio_observacional" title="Estudio observacional – Spanish" lang="es" hreflang="es" data-title="Estudio observacional" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D9%85%D8%B7%D8%A7%D9%84%D8%B9%D9%87_%D9%85%D8%B4%D8%A7%D9%87%D8%AF%D9%87%E2%80%8C%D8%A7%DB%8C" title="مطالعه مشاهده‌ای – Persian" lang="fa" hreflang="fa" data-title="مطالعه مشاهده‌ای" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%AA%E0%A5%8D%E0%A4%B0%E0%A5%87%E0%A4%95%E0%A5%8D%E0%A4%B7%E0%A4%A3_%E0%A4%B5%E0%A4%BF%E0%A4%A7%E0%A4%BF" title="प्रेक्षण विधि – Hindi" lang="hi" hreflang="hi" data-title="प्रेक्षण विधि" data-language-autonym="हिन्दी" data-language-local-name="Hindi" class="interlanguage-link-target"><span>हिन्दी</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Kajian_observasional" title="Kajian observasional – Indonesian" lang="id" hreflang="id" data-title="Kajian observasional" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-lt mw-list-item"><a href="https://lt.wikipedia.org/wiki/Steb%C4%97jimo_tyrimai" title="Stebėjimo tyrimai – Lithuanian" lang="lt" hreflang="lt" data-title="Stebėjimo tyrimai" data-language-autonym="Lietuvių" data-language-local-name="Lithuanian" class="interlanguage-link-target"><span>Lietuvių</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Studie" title="Studie – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Studie" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Badania_obserwacyjne" title="Badania obserwacyjne – Polish" lang="pl" hreflang="pl" data-title="Badania obserwacyjne" 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/Ci%C3%AAncia_observacional" title="Ciência observacional – Portuguese" lang="pt" hreflang="pt" data-title="Ciência observacional" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%9E%D0%B1%D1%81%D0%B5%D1%80%D0%B2%D0%B0%D1%86%D0%B8%D0%BE%D0%BD%D0%BD%D0%BE%D0%B5_%D0%B8%D1%81%D1%81%D0%BB%D0%B5%D0%B4%D0%BE%D0%B2%D0%B0%D0%BD%D0%B8%D0%B5" title="Обсервационное исследование – Russian" lang="ru" hreflang="ru" data-title="Обсервационное исследование" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-th mw-list-item"><a href="https://th.wikipedia.org/wiki/%E0%B8%87%E0%B8%B2%E0%B8%99%E0%B8%A8%E0%B8%B6%E0%B8%81%E0%B8%A9%E0%B8%B2%E0%B9%81%E0%B8%9A%E0%B8%9A%E0%B8%AA%E0%B8%B1%E0%B8%87%E0%B9%80%E0%B8%81%E0%B8%95" title="งานศึกษาแบบสังเกต – Thai" lang="th" hreflang="th" data-title="งานศึกษาแบบสังเกต" data-language-autonym="ไทย" data-language-local-name="Thai" class="interlanguage-link-target"><span>ไทย</span></a></li><li class="interlanguage-link interwiki-zh-yue mw-list-item"><a href="https://zh-yue.wikipedia.org/wiki/%E8%A7%80%E5%AF%9F%E7%A0%94%E7%A9%B6" title="觀察研究 – Cantonese" lang="yue" hreflang="yue" data-title="觀察研究" data-language-autonym="粵語" data-language-local-name="Cantonese" class="interlanguage-link-target"><span>粵語</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E8%A7%82%E5%AF%9F%E6%80%A7%E7%A0%94%E7%A9%B6" title="观察性研究 – Chinese" lang="zh" hreflang="zh" data-title="观察性研究" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li></ul> </section> </div> <div class="minerva-footer-logo"><img src="/static/images/mobile/copyright/wikipedia-wordmark-en.svg" alt="Wikipedia" width="120" height="18" style="width: 7.5em; 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