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Notes on Regression Discontinuity Methods - [athena.sas.upenn ...

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Two Types of Designs<br />

• Fuzzy Regressi<strong>on</strong>-Disc<strong>on</strong>tinuity (FRD) Design<br />

• Prob of receiving treatment need not change from 0 to 1 at<br />

the threshold, but there there is a disc<strong>on</strong>tinuous jump in the<br />

probability, so that<br />

limx↓cE(Wi|Xi = x) − limx↑cE(Wi|Xi = x) = 0<br />

or,equivalently,<br />

limx↓cPr(Wi = 1|Xi = x) − limx↑cPr(Wi = 1|Xi = x) = 0<br />

• Treatment effect can be obtained by the ratio<br />

τFRD = lim x↓cE(Yi|Xi = x) − limx↑cE(Yi|Xi = x)<br />

limx↓cE(Wi|Xi = x) − limx↑cE(Wi|Xi = x)<br />

(3)

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