reliableelectronic data. Kindergarten participation was also excluded sinceit is universal.Evidence of selection bias in ECCE choices compelled us to usePropensity Score Matching (PSM). Propensity Score Matching wasused to estimate the effect of public ECCE on academic achievementby: (a) matching children who attended public ECCE (N = 31,947)with children who did not attend ECCE programs (N = 54,571)according to their probability of attending public ECCE (propensityscore) and; (b) comparing their SIMCE 2008 test scores.