To the Editor:
We read with respect the article by Ruopp et al. (1) that has questioned the methodological approach of our previously published review (2) on the use of aspirin in in vitro fertilization cycles. We disagree with the authors in that random-effects models should only be used in the absence of inter-study heterogeneity. With fixed-effects models, it is assumed that there is a sole common effect estimates for all studies, i.e., the true effect of treatment, in both magnitude and direction, is the same value in every study. Read the rest of this entry »
