An Evaluation of Instrumental Variable Strategies for Estimating the Effects of Catholic Schools
Several previous studies have relied on religious affiliation and the proximity to Catholic schools as exogenous sources of variation for identifying the effect of Catholic schooling on a wide variety of outcomes. Using three separate approaches, we examine the validity of these instrumental variables. We find that none of the candidate instruments is a useful source of identification of the Catholic school effect, at least in currently available data sets
Altonji, Joseph G., Todd E. Elder and Christopher R. Taber. "An Evaluation Of Instrumental Variables Strategies For Estimating The Effects Of Catholic Schooling," Journal of Human Resources, 2005, v40(4,Fall), 791-821.