A Comprehensive Review and a Meta-Analysis of the Effectiveness of Internet-Based Psychotherapeutic Interventions Azy Barak Liat Hen Meyran Boniel-Nissim Na’ama Shapira ABSTRACT. Internet-based psychotherapeutic interventions have been used for more than a decade, but no comprehensive review and no extensive meta-analysis of their effectiveness have been con- ducted. We have collected all of the empirical articles published up to March 2006 (n ¼ 64) that examine the effectiveness of online ther- apy of different forms and performed a meta-analysis of all the stu- dies reported in them (n ¼ 92). These studies involved a total of 9,764 clients who were treated through various Internet-based psychological interventions for a variety of problems, whose effec- tiveness was assessed by different types of measures. The overall mean weighted effect size was found to be 0.53 (medium effect), which is quite similar to the average effect size of traditional, face- to-face therapy. Next, we examined interacting effects of various Azy Barak, Liat Hen, Meyran Boniel-Nissim, and Na’ama Shapira, Faculty of Education, University of Haifa, Aba Hushi Rd., Mount Carmel, Haifa, Israel. We are indebted to Ronnen Fluss for his assistance in analyzing the data. Address correspondence to Azy Barak, Faculty of Education, University of Haifa, Aba Hushi Rd., Mount Carmel, Haifa 31905, Israel. E-mail:
[email protected]. Journal of Technology in Human Services, Vol. 26(2/4) 2008 Available online at http://jths.haworthpress.com # 2008 by The Haworth Press. All rights reserved. doi: 10.1080/15228830802094429 109 110 JOURNAL OF TECHNOLOGY IN HUMAN SERVICES possible relevant moderators of the effects of online therapy, includ- ing type of therapy (self-help web-based therapy versus online com- munication-based etherapy), type of outcome measure, time of measurement of outcome (post-therapy or follow-up), type of prob- lem treated, therapeutic approach, and communication modality, among others.