CINXE.COM

<!DOCTYPE html><html lang="en-US"><head><title>Just a moment...</title><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=Edge"><meta name="robots" content="noindex,nofollow"><meta name="viewport" content="width=device-width,initial-scale=1"><style>*{box-sizing:border-box;margin:0;padding:0}html{line-height:1.15;-webkit-text-size-adjust:100%;color:#313131;font-family:system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,Arial,Noto Sans,sans-serif,Apple Color Emoji,Segoe UI Emoji,Segoe UI Symbol,Noto Color Emoji}body{display:flex;flex-direction:column;height:100vh;min-height:100vh}.main-content{margin:8rem auto;max-width:60rem;padding-left:1.5rem}@media (width <= 720px){.main-content{margin-top:4rem}}.h2{font-size:1.5rem;font-weight:500;line-height:2.25rem}@media (width <= 720px){.h2{font-size:1.25rem;line-height:1.5rem}}#challenge-error-text{background-image:url(data:image/svg+xml;base64,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);background-repeat:no-repeat;background-size:contain;padding-left:34px}@media (prefers-color-scheme:dark){body{background-color:#222;color:#d9d9d9}}</style><meta http-equiv="refresh" content="390"></head><body class="no-js"><div class="main-wrapper" role="main"><div class="main-content"><noscript><div class="h2"><span id="challenge-error-text">Enable JavaScript and cookies to continue</span></div></noscript></div></div><script>(function(){window._cf_chl_opt={cvId: '3',cZone: "pubs.aeaweb.org",cType: 'managed',cRay: '8e9f02632b6c91a5',cH: 't.D9ijmFbor72ckeGJdK9nUKYPUuW1qQjopRIzb44nc-1732845681-1.2.1.1-OeXu_MYKpna52Zcn16nCdG_lCmGlqlucyeXc5HbXnpfos_UckKoEoCbsAToelZA8',cUPMDTk: "\/doi\/10.1257\/aer.98.2.230?__cf_chl_tk=1vluVwxO7TsJO4ZMrlJJSox6Pc7DfnwaSwJEGExYtfE-1732845681-1.0.1.1-N.hM7_XPk4w9Xb6WI38KXi2BUJb3b7PcMhPFQGWP5t8",cFPWv: 'b',cITimeS: '1732845681',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "",fa: "\/doi\/10.1257\/aer.98.2.230?__cf_chl_f_tk=1vluVwxO7TsJO4ZMrlJJSox6Pc7DfnwaSwJEGExYtfE-1732845681-1.0.1.1-N.hM7_XPk4w9Xb6WI38KXi2BUJb3b7PcMhPFQGWP5t8",md: "E1j.OCQTaEKRBFn0_4lM7aVZ.d5qIoV1HHf3aneUfbg-1732845681-1.2.1.1-VBmw5qn5AvYycSENewtl7RYEIqQhMpWymBAT0DdbLG6fe2DHsIQCnTGEyvs1cy_jCfgvsMpn8NR7plJcpreXqDBFCkceYnFa49qeI73Ujn2UK9AzlkxHuNTWl2n4oxqE53WW.WqvJeEK4xHlnOpL_bjJdE5nQ5LI6SsqqPUXAK.aPxQ_FlGkUiTDygNvLrd77XxcaZck92Lo57sb7v8gwavcU2rgJ9iXLDF4.3WiD8dGIO9ZYnNTzIgWhRanPbi5xMvjfnx0pyNwsmIIFGm03KphqthSI3IXOAetr61pHUemehKP1sXyvtjWW71ki5FFdLbdLhzcsV_H9AMNOfs.uukPhVAPmjn0mgFdEqAXYYwDsiggdFH7cggWssOqdLElkwQkY5RatmPrZwrTrfQlzhGKnPURraA9vdYdAC_48k1O_ta9p3Fp3PjAcwPxB2dsu3cIhslBE4GHMZyY2t95fkf5_JQBCVSluUL5G.NtdomWBOKxFxeaMpwpsnXhbc090kD8CB0TeoHtPPYj9Jw16nCRVGQauaEdEQ.AcLNtv0IR1JGcVTV9Cwk0xs.xPNO_GOi5RM3ZjRS1zbmgyK7WJXdCLC53P.og9AjGpNMWbSyA57g_OcO2TKduDXZa3Xg_.HReahreXTJ6VZyqS6jObrxOGykuxHfT2R_5sjHLSIR0Jr5ktaxcCsn47tYBNCaEe.ynhqLVfsKflcI59sxQ.wcnM0B1IUTJtGoCfYlhBLgiXC_9ahsSvzgb.MbQYqs4gSi7s.fbwEyk5Wy2evV5tILlG3Rb4oJqkyeyEpoWL84b4LH1d04xSIFqoOmvCT0kjj_uEUAvuAYisci4HyehE.IanqXoelNVsrVF5BpaLpdp.TVxNVIeX8uhuFvzFYI5Hv0rV0nhtuluFXhmVAPBFJaLRXieJFvZzNVY9YX6nbScmyw87jsFKoqD8AqlUmqMAG4Tnb.H05TQOHl28jcnMWVbGshb0yqv1jflbn_0tNMZvWWRWwbcwiO02NNgkupxFpP0BFWlUK4rxvu3R6Gx6DhJJ7PqsCh.CihDNY4f6QwWF6KNDOq8rWU1mumpSFmQ51ncGKl_lIE6zW22AMKzJVanYPRE_rl3te0sCeun1uTuhC7KsGFjgnWLxzI1Hah5oLkEdgC3OME_rZt0JCYzSHpJAdxvXR.1j4_pKTVYOvDNSnXvu53s1ipPyuJ8AsxMy4Y.zX35xiNfQLTTGS6kLLggrvm9rsY8UdJzrHvuTNw4IO53aCl.6mvUX90Xe9JbO5fRhm.7gQyt_xikKWbW44G_eEI7nZgTRzvTWnP8j.m4EmM7SdG0angbOll6Zch7RV8CeC6GHgAhvQdg1jaEI4m.P5qO6i75UmrsWxQGSVi4dffbHGd47hi2hP5TR8dyaNb0cEpQlMkSqXmu8PqUn16n4Do1IBpzPOd3UD758Ib_2ZpRXxfgFe5fvE7lr24NeImGzt.Z8y4EoKX2Zc.8c.3Fa9qMDdiyeNvVStohP3xZf_rTXFSJSEZdSsG119jK.J3RFAVpo4aRZGNqpzf.5LC2uvKNfrOX5LpY1c5LLx4bSLXdFi7CK8gEEVTZmcoZGBj2t7pK3TF_ybpKrzIjWMpB9JvBwIMRFipDpvnFGNL2iUHfooRpNypySSZvXlQ0X94R.cXh4n8yCC0aM0IHUyeKbXTGAoubvPrI2ADdTzTJWFCe7slDu9D.oin80V6WCvZkIA.fGZKCcWlSw4TQZ9BBZK9WXJDBvYVyL6R372pZlrzYQXqIscKUGyQ.RWfwQ2J6jZCIBW93x6lA5CD1GadGl6rnHmt0pLtW321tDpHTGyMZ1.bGhdv4.H7CooRCs1KcqlmkAshm6brXE8whHlgsjtA057QhHvYxeTr8CWBfKJTpJtX78z1Cih5X.mtQkP6pfcjCqMtANcJ.boYQOaVjxht7b3.XnxnLffymeJ5ALXwyzqDuBv94MxVgyWsriVID6ifQlhtgSiE4MQxSjs8P66lPg2Ev.LA3rI1z_zFnQOqrzlIcUZPl2FgYCBgdxkFH1OSVZFoWwB_zCuwkjShhh.kYVhlQVXfvsVMNBbz69ILv7UP6ncAXqx4ylNTXEvj4o2FzD9TWb1mKswd9T5zQY8dcwNhRjxtiKwDXk2mHZRfKgNJJ9ydfGHpsCaJxkFP8k5S8nlbLcnfjVCv8MyiR8lMp511YDfDnvOfUB_Gb5NqBdt1RUsqqxk7Gb93.79afhF54bSr9lQRsaFNvqEB8_CjEb5.mDCL1njZiZi6BCwdKXKsEZXsfol7rgEagY.wGuIJLxexJHCjiVWsDugQkyvTCVZxsGhvUVJPLjwAIJczVy5pS.4Pfub_fTX29dsdzqbtm9paY_muI5F9.b_N3rQyPaxltxx2htLf.sJCOcnhiZXqHwxwPDMxoA7w2yRVtHIoQuAovo6tj3z15VrsqOa0TJVNprlim65BuwqSY49j9ii0ZD9mr9jrOJIIwDryoDC9Sw.txOcrb373jHh6jUN62mknq_3FgMquDTnj4okP.NRzp.GFYNxTvtGPkxm1XF_.84iR96Uo6yv8JU044mgN2B8zL5Gm3BAWFyQuRzGuNd_oJMRgjSCsI8vrqarS9P45PeH0wDVvmFy_S.Qt1qoTpVuRs1bbQWWzkpo2ZBuOYfJMl_ObJIxcjS5onvpkl5t0eYa9eYvBMmOF2VN2H5m31x00oxPcSifjONVDjMsCJfJedCZZCFKSyB9PpgAp2PHdtzbyNCmHs5RUvdltOOd8GGNYjmw5nIgpOZPQKiJFOgBdq4E6jznabPkyx_MfXdCvGELSmoNbmQi_3qI4X9G3GY8qkClBGKaKtdTa_kl93pZvRhzX_9L8V1RCBvVzVVdqkaax_EQxgh9TrMdX98.JvoH82dy8TPUJQyNbScfX3SE6DIL85frUcO3vNJ63Ck1eY3EYdUhsLThx3sAeB28TVKuSPG80nBSOxx80",mdrd: "WBZ3iTJTleHG86nsONMR8IesOQWvP3Oc.wxlY3n1dqw-1732845681-1.2.1.1-TqDFMFBN235NalBp6DRI_b3coQZGTpGyN0Tht3nuMAUl2X6EQLwWInHoxTB9iwSlK6Cz9yItqoGvt_aji12vqIJGYol9957FRhlkQw4NWOVPRxU7xe1jaGwn.w6WOXnjDNnUzWs.N92uO0sGMkjE_NBfRYRBhpZYss55RNIhjDlvG9fPQk0Yd946aZbZboMUSzfnAMHIIan7zjI2xjrDJF1nk74T75a7pNFBoXvoZiynosZioCsh.1Rq4rl3QBLU1IFFFd0f1Einf1fzOK5ZEyIF9Py1d7VLk7dREmoZdn3UDySUH7rrOeZ0GV.jcSC867UJIjsvxgiCB7ZS0JDBvy_IL1hUtm.ggOCc9TzVawB0NZf6FS.kS8XU42RnCCjERnGIJ3xX2pX8PfDEiS_KMcs6lkkBgPNX_Ci24URhA569YSkaGmj1KXH4fjKmfrOOVKmEdyw_pJWh9Kjeufhx6LM0Yeun8YQR.XDZLFLX7qIDjm_UoCtIPNT741OQX6SntfSlJ2g2wO1kUB7O3aN8v3.cDpYvpUiwXLbSbsiGrl6s8A8WGBCJxMj1Ufne5dAWAFBuDi6UUDmClt25JeGCcc_9AiUlkmhG7GjCox.CyEEFEy5PL4kdnEoj2ZdWADdLaz1pRbhSaf4.ct_pqQePpYCyFYlhdZAe4URdCm_kEYNIFdn84N0PId1dgoakv6jKM5sO0aMUmksfjYRIQUACNCDjorLCipJ6tb7dVkpjfz654ElSXsqsKGyEUPDSfZdcLNXeHR2GpF.vdOjbv31LHAqwcDelk6hBvr99GwdIWIek2iuftgG_mpY4fTW2OLP.xAA2Qgt19eSZMt8tSw4exVq7liYitpuQs9XZqetjiebCUmFvUOqZb9rMmu0n.CQovITM59LlaE0si7gjPcug327.oDjFASjsXYAvJyBn7mpoKHBNBfSSGGGXXuE.p1sb910FelWYvjAwcGRKJfPeEFFml4FG6jPXBCoWF2nsmpTrR6Ur51dZErrlYTpUKhPCxgnNY8Pqhu2cp1wUcc1y2Eq94aI2fGA1Pq0HIIctVRxp..N2ywX1sj096V5C.DZsAW90IvlHuo14TyiINwkOuXz8q2kctn9rkZDMFQzcyXYyDpYKalM7GgPPlf3UglbVR7Mrn8NqeKJrLGgT9RFjMiRgFIMwUU60RSjyGwuX3miGszF03gb9BYV5O3EJoYETgiXNnw9RR7RIH.mcz2qeAV5lf41jZlFI9gJoSoE4Kj6DCAZCRXrT.idUwzSmTJxvd_K29PGNuwvK47gnBAdfO2Nah66H787cg7h03g_6kyWqZ4aHBrhbPR7rvUrecWz5moOF1swNgK0Laoq5zYspZ4yEzVFJjMLSMQ8xKzEC7buKfClbASYPplus6I7XYfb4tuL0.vPSSVWiAM3soj8iJNsrH8HJyUYNgh1t_QbHLZ.bpfUdxycmOjCCbR_LYpdKGWQZSiIONxtWjfAdMxoh.Qi1Ob_yF9S08AXVdBQ96aRGfni3H6_BsB4yTMoS1LRh4el3jmu4iAlVAGIzn2ZF4SdfQCVzfuzEbLDzI0MJJKDxArukmbiRvmcMibXLODkZz2jZLnV3haRHcbJD1fd3QFaZoa047wMTG6U3CEgZgy6mMR50yxwqm4RvEPRC4GzLLTCmWbM5yvxqhRqJ04Voxn.8ShhJLPyV7.zFkFxdFshLYeMjuDWZYP6L9Tcyup7f5XNRuWW.uPjwZ3CM5D_rFub2uMHDDL944BeJn3C5ntnmf_8V7ZqtzvZ3Ta1zkl5w50P4dnKYojUTQqXDjsnzrCP1o2TkfKDv7iboTx6HbTn_J1TK6Tl_sN_6ooiy50NQABak6FgbLJMF39xxr7AFraex5L1Hi6xBFq1RsJGYFQ5PU.Ma1bMsgaqDvJYwqhWvTv8_cw3i29QYQdvVEBtb6XW1yL7bmfn.6Xx.8R9aJv5RM9t8YJrbyhb.K_cLwd9j"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=8e9f02632b6c91a5';window._cf_chl_opt.cOgUHash = location.hash === '' && location.href.indexOf('#') !== -1 ? '#' : location.hash;window._cf_chl_opt.cOgUQuery = location.search === '' && location.href.slice(0, location.href.length - window._cf_chl_opt.cOgUHash.length).indexOf('?') !== -1 ? '?' : location.search;if (window.history && window.history.replaceState) {var ogU = location.pathname + window._cf_chl_opt.cOgUQuery + window._cf_chl_opt.cOgUHash;history.replaceState(null, null, "\/doi\/10.1257\/aer.98.2.230?__cf_chl_rt_tk=1vluVwxO7TsJO4ZMrlJJSox6Pc7DfnwaSwJEGExYtfE-1732845681-1.0.1.1-N.hM7_XPk4w9Xb6WI38KXi2BUJb3b7PcMhPFQGWP5t8" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>