Cost-effectiveness, therefore, becomes a critical concept as the combination of both effectiveness and efficiency. To justify the continued use of workbooks in clinical settings, as well as to promote more stringent empirical examination of this issue, this chapter examine if workbooks show any effectiveness. Meta- analytical methods for the cumulation and examination of research studies can thus provide an alternative, and in many ways preferable, approach to evaluate a research literature. Meta-analysis is a statistically based approach for generating effect size estimates by aggregating effect size information from all available sources. There are, however, some unique difficulties posed by the literature on workbooks.
Vast differences exist between studies in overall design and quality of methods and statistics used.
Studies were also required to contain some outcome measure of health, although, for the purposes of this chapter, we defined health in the broadest possible terms. Studies also had to contain statistical information necessary to calculate an effect size. Magnitude and significance of the overall mean weighted effect size was computed for all outcomes and all studies. One effect size was computed for each study by generating effect sizes for each outcome in the study, and then averaging across all outcomes. This analysis supports the use of workbooks as additions or as alternatives in preventive and psychotherapeutic practices, making them tools for secondary prevention.