“…The second criterion was that the intervention effect had to be measured and reported quantitatively to enable the calculation of effect size. Although twelve studies originally failed to meet this criterion (Andersson, 1985; Brown, Allen, Dwozan, Mercer, & Warren, 2004; Clarke, Clarke, & Jagger, 1992; Evans & Jaureguy, 1982; Evans, Smith, Werkhoven, Fox, & Pritzl, 1986; Jones, Hobbs, & Hockenbury, 1982; McLarnon & Kaloupek, 1988; Routasalo, Tilvis, Kautiainen, & Pitkala, 2009; Seepersad, 2005; Stewart, Reutter, Letourneau, & Makawarimba, 2009; van Kordelaar, Stevens, & Pleiter, 2004; van Rossum et al, 1993), attempts to recover quantitative data from the authors were successful in two cases (Evans, Smith, Werkhoven, Fox, & Pritzl, 1986; Seepersad, 2005). The third criterion was that each study had to report original data not reported in another paper to avoid inflating effect sizes.…”