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Regression-Discontinuity Design - Institute for Policy Research

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IS Wong et al. a Fallible RD or<br />

Institutional Cohort <strong>Design</strong>?<br />

Fallible RD<br />

Institutional Cohort <strong>Design</strong><br />

Children’s birthdates and state cutoffs are<br />

a mostly deterministic mechanism <strong>for</strong><br />

treatment assignment <strong>for</strong> the subpopulation<br />

of units near the cutoff, but<br />

should probe <strong>for</strong> selection effects.<br />

The RD focuses on the comparability of<br />

units at the cutoff<br />

Leads the researcher to look <strong>for</strong><br />

discontinuities in potential outcomes at<br />

the cutoff<br />

Assume that children’s birthdates and<br />

state cutoffs are not a deterministic<br />

mechanism <strong>for</strong> treatment assignment, so<br />

we should regard this design as an<br />

institutional cohort design approach.<br />

An institutional cohort design focuses on<br />

the comparability of all 5‐year‐olds in<br />

kindergarten versus all 4‐year‐old cohorts<br />

in pre‐K<br />

Leads the researcher to consider<br />

matching methods between cohorts to<br />

improve internal validity (will address<br />

later) …

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