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[Correspondence] Systematic reviews and research waste

In their letter,1 Ian Roberts and Katharine Ker made three assumptions: that small clinical trials are all of poor quality; that all large, multicentre, well funded trials are of exemplary quality; and that meta-analysis cannot ameliorate the low power of small trials. None of these assumptions are documented. Although many clinical trials do have methodological flaws, many do not, and this issue is addressed in systematic reviews with sensitivity analysis. Certainly, the aims of meta-analysis are to achieve increased statistical power and better quality assessment and to obtain a summary statistic.