阅读文献并回答问题

阅读文献，回答下列问题： 1. What was the authors search strategy? What do you think about this search strategy? Would you adopt the same strategy, and why? 2. What were the inclusion criteria for inclusion of studies in this review? 3. a) Heterogeneity among included studies is often assessed in meta-analysis. What is heterogeneity, and why is the assessment necessary? b) Which parameter in Figure 2 measured