Approximations to a conservative inverse chi-square procedure for combining p-values in integrative research

The use of p-values in combining the results of independent studies often involves studies that are potentially aberrant. This suggests the use of a statistic which trims some of the smallest and largest p-values. Here we provide two convenient approximations to the exact distribution of the trimmed Fisher statistic. The first utilizes Pearson's system of curve classification, while the second is a normal approximation.