“…A second explanation is that meta-analysis traditionally has had difficulty aggregating the results of the multivariate quasi-experimental models typically used in the social sciences. Nevertheless, over the past several years, meta-analytic studies have begun to appear in leading journals in economics (Card & Krueger, 1995;Kremers, Nijkamp, & Rietveld, 2002;Smith & Huang, 1995), political science (Church, 1993;Gerber, Green, & Nickerson, 2001;Lau et al, 1999), and sociology (Crain & Mahard, 1983;Stanley & Jarrell, 1998;Wagner & Gooding, 1987). In addition, meta-analysis is increasingly being used by policymakers when making regulatory decisions (Berlin & Colditz, 1999).…”