Meta-Analysis Clause Samples

Meta-Analysis. Insights gained from meta-analysis can be useful to resolve several issues faced in combining surveys, as survey heterogeneity, planning data collection, and pooling data across surveys (▇▇▇▇▇▇ 1999). ▇▇▇▇▇ and ▇▇▇▇▇▇▇▇▇ (1990) define meta-analysis as “the practice of using statistical methods to combine the outcomes of a series of different experiments or investigations”. It implies four steps: identifying all relevant studies; assessing study quality; dealing with study heterogeneity; and summarizing the results. ▇▇▇▇ (1998b), in the context of constructing an average birth rate for a continent using separate country birth rates, proposes three options for pooling multinational samples that are directly comparable to the three main meta-analytic models for combining study effect sizes: fixed effects (equal weight to each country’s estimate); equal effects (all subjects are independent and of equal importance); and random effects (weighed averages of the study proportions). When similar data are collected in several sites (cities, provinces or districts of one country) of a combined population, but not in all of the sites, alternative treatments of them are possible (▇▇▇▇ 1999a). In combining separate sites three decisions must be made: the allocation of sample sizes, whether the samples should be combined and what weighting to use. These are expressed as follows by ▇▇▇▇.