We extend existing gene enrichment tests to perform adverse
event enrichment analysis. Unlike the continuous gene expression data,
adverse event data are counts. Therefore, adverse event data has many zeros
and ties. We propose two enrichment tests. One is a modified Fisher's exact
test based on pre-selected significant adverse events, while the other is
based on a modified Kolmogorov-Smirnov statistic. "Adverse event enrichment
tests using VAERS" Shuoran Li, Lili Zhao (2020)