Simulation parameters Average number of cases Mean of vaccination effect coefficient
(standard error)
Empirical power (%)
α σ   CPa/FEb GEEc CP/FE GEE
-5 1 510 0.682 (0.159) 0.687 (0.159) 96 97
  1.5 936 0.664(0.127) 0.662(0.132) 100 100
-6 1 188 0.668(0.279) 0.668(0.280) 68 68
  1.5 351 0.665(0.207) 0.661(0.209) 87 87
-7 1 69 0.600(0.516) 0.599(0.516) 35 35
  1.5 130 0.661(0.355) 0.655(0.356) 55 54
-8 1 26 0.719(0.624) 0.718(0.624) 17 17
  1.5 48 0.618(0.574) 0.611(0.578) 26 26
aCP, conditional Poisson model.
bFE, fixed effects model.
cGEE, generalized estimation equations.
Table 2: Mean of vaccination effect coefficient (standard error) and empirical power from 1000 simulations with true β1=0.693 when individual-specific random effects have a normal distribution.