Meta-mining: The political economy of meta-analysis

Meta-analysis studies the literature reporting estimates of one parameter, which at present is assumed positive. The purpose of the analysis is to find the best meta-average, which corrects the mean of the estimates for bias. The two main biases are: (i) Publication bias, where the correction nearly always makes the average smaller. (ii) Omitted variable bias, where the correction typically makes the average larger. Consequently, the bias is likely to increase if the correction is for the wrong bias. This allows a game of meta-mining to be played. A case study demonstrates the scope for meta-mining, and that it has been done. The game of meta-mining is surely against the purpose of meta-analysis.