“…The evidence is overwhelming that preschool programs can work to increase performance in the early school grades (Campbell & Ramey, 1994;McCarton et al, 1997;Reynolds & Temple, 1995;Weikart, Bond, & McNeil, 1978). Evidence also suggests that these programs can positively affect later high school graduation rates, labor force participation, stable household formation, and criminal behavior (Barnett, 1995;Campbell, Ramey, Pungello, Sparling, & Miller-Johnson, 2002;Currie, 1995;Ludwig & Miller, 2005;Schweinhart et al, 2005; for reviews, see Barnett, 1995; of this study is to model for readers how an RDD should be carried out to ensure that its assumptions are met.…”