The Effect of Portfolio Use on Academic Achievement: A Meta-analysis
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It is a meta-analysis study, searching the effectiveness of portfolio use in teaching. The sample, selected through an exhaustive search, consisted of 24 studies, including the studies conducted in overseas. The data complied through a coding form and statistical findings converted into the effect sizes. The codings were carried out by two researchers; the consistency was near perfect, as calculated by a Kappa statistics of .90. The analyses were classified into two headings as overall analysis (24 studies) and cumulative analysis (46 comparison groups). Considering the technological developments in time that was relevant in the current study, Random Effects Model was applied in the current analysis; effect sizes for general and cumulative data were calculated, heterogeneity was tested through Q statistics, and I-2 was calculated to determine the degree of heterogeneity. MetaWin 2.1 and SPSS 17.0 were used for analyses. Publication year, subject area, publication type, application type, education level and subject area were the moderator variables. The results were evaluated both in general and cumulatively and indicated heterogeneity for general analysis and homogeneity for cumulative analysis. However, none of the moderators explained heterogeneity in general analysis. According to the results, portfolio use has a large, positive impact on academic success. In addition, Rosenthal Approach indicated the validity of the results. Findings indicated that to declare the findings null there was a need for an additional 3524 and 5725 studies with reverse findings for general and cumulative analysis, respectively.