Students in a School System with Scores Below 70 on a Diagnostic

Multiple Choice

Students in a school system with scores below 70 on a diagnostic test are required to attend an early morning math program .At the end of the year, researchers compared the math grades for these students with those of students who scored 70 or above on the initial diagnostic test, controlling statistically for diagnostic test score .This type of research uses

A) Propensity score matching
B) Instrumental variables
C) Regression discontinuity
D) Difference-in-differences