We inspected the references of the articles for additional relevant articles, and we contacted the authors of the articles to ask for any unpublished data that maybe appropriate to this meta-analysis, and an author pointed out an 11th study. The articles included unpublished data, published data, and dissertations. Sternberg (2000) recommended including unpublished papers and dissertations in
meta-analyses as this may avoid a bias toward studies that have found significant results. For articles that did not provide enough information to conduct the meta-analysis, we asked the authors to provide the needed information.