Fig. 4

Empirical power of covariate models from balanced design with N _D=1  = 10 and μ _D=0  = 1000. The power of Negative Binomial with true dispersion (NB), and Firth’s Logistic (FL) regressions at significance level 0.05 and 0.01 is shown in the figure. Black dotted horizontal lines represent 95 and 90% power. The odds ratios between covariates and case–control status (CovOR = 1.2 and 5) are partitioned by vertical black dotted lines. The number covariates (0, 1, 2, 3, 5 (, and 10)) in the model are positioned within each CovOR. Dotted lines within each symbol represent the 95% confidence interval. a Balanced design from N _D=1   = 10, μ _D=0  = 1000, dispersion = 0.01, and log2fc = 0.3. b Balanced design of N _D=1   = 25, μ _D=0  = 1000, dispersion = 1, and log2fc = 2