We conduct a study under 2,400 third grade students at three large secondary
comprehensive schools to evaluate a gifted and talented (GT) program with selective
program admission based on past achievement. We construct three complementary
estimates of the programís impact on student achievement. First,
we use the fragmented GT program implementation (in different tracks at different
schools) to get difference-in-differences (DD) estimates for all students
above the admission cutoff. Second, we use the GT admission rule to get regression
discontinuity (RD) estimates for students near the admission cutoff.
And third, we combine the DD and RD designs to estimate how the programís
impact varies with past achievement. We find that all participating students
do better because of the GT program. Students near the admission cutoff experience
a 0.2 standard deviation gain in their grade point average. Students
further away from the admission cutoff experience larger gains.