When the expected counts are small, it common to have meta-analyses where all studies have zero counts in the numerator. In such cases, the discrete likelihood method (random effects logistic regression) fails to converge. Because simulations that fail to converge do not contribute to the calculations of proportion bias, proportion RMSE and coverage, these metrics should be interpreted with caution.

From: Results

Cover of Simulation-Based Comparison of Methods for Meta-Analysis of Proportions and Rates
Simulation-Based Comparison of Methods for Meta-Analysis of Proportions and Rates [Internet].
Trikalinos TA, Trow P, Schmid CH.

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