Marianne Welmers

Chapter 2 28 Records identified through database searching (n = 2447) Screening Included Eligibility Identification Additional records identified through other sources (n = 51) Records after duplicates removed (n = 2138) Records screened (n = 2138) Records excluded (n = 2096) Full-text articles assessed for eligibility (n = 42) Full-text articles excluded (n = 14), with reasons: M age of youngest generation in therapy > 21 (n = 2) Family aspect of treatment not clearly defined (n = 4) No sufficient data to compute effect sizes for therapeutic outcome (n = 8) Studies included in quantitative synthesis (meta-analysis) (n = 28) Figure 1 Flow Diagram for the Search and Identification of Studies Coding of Studies In order to code effect sizes and moderating variables of included studies, we developed a coding form, followingguidelines asdescribedbyLipsey andWilson (2001). All study, sample, and methodological features shown in Table 1 and 2 were coded for moderator analyses. If information on certain moderating variables was missing in the study report, authors were contacted to retrieveadditional information. All studies thatmet inclusioncriteriawerecoded by the first author. For 39% ( k = 11) of the 28 studies effect sizes and all includedmoderator variables other than study quality (see the next paragraph) were independently coded by the second author in order to assess interrater reliability. The Intraclass Correlation Coefficient (ICC) for double coded effect sizes ( n = 127) was .82, average ICC for continuous moderator variables was .95, and average Cohen’s Kappa for categorical moderator variables was .70. Differences in scores for effect sizes were discussed until agreement was reached.