Regression-Discontinuity Design - Institute for Policy Research

Fuzzy RD Designs
• Requires a discontinuity in the probability of
treatment at the cutoff such that
limE[D i
| z i
= z c
] ≠ lim E[D i
| z i
= z c
],
but not a 1 to 0 change.
z↓z c
z↑z c
• In practice, this means some individuals
“crossed‐over” treatments or did not “show‐up”
for treatment.
• Hahn, Todd, and van der Klaauw (2001) show
that when fuzziness occurs, the local average
treatment effect (LATE) may be inferred for the
subset of individuals who are induced into
treatment at the cutoff.