Objective Study how to quantify the bias of each study and how to estimate them. Method In the random-effect model, it is commonly assumed that the effect size of each study in meta-analysis follows a skew normal distribution which has different shape parameter. Through introducing a shape parameter to quantify the bias and making use of Markov estimation as well as maximum likelihood estimation to estimate the overall effect size, bias of each study, heterogeneity variance. Result In simulation study, the result was closer to the real value when the effect size followed a skew normal distribution with different shape parameter and the impact of heterogeneity of random effects meta-analysis model based on the skew normal distribution with different shape parameter was smaller than it in a random effects metaanalysis model. Moreover, in this specific example, the length of the 95%CI of the overall effect size was shorter compared with the model based on the normal distribution. Conclusion Incorporate the bias of each study into the random effects meta-analysis model and by quantifying the bias of each study we can eliminate the influence of heterogeneity caused by bias on the pooled estimate, which further make the pooled estimate closer to its true value.

Citation： FUJin-yu, QINChao-ying. Quantitative Analysis of Bias of Each Study in Meta-analysis. Chinese Journal of Evidence-Based Medicine, 2016, 16(9): 1112-1116. doi: 10.7507/1672-2531.20160169 Copy

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