A comparison of two methods for estimating prevalence ratios

Table 2 Estimated size and estimated power for log-binomial and Robust Poisson methods*

Prevalence at X = 5	Method	Zero Slope	Medium Slope	High Slope
		Size^†	Power^†	Power^†
0.3	Log-Binomial	0.054	0.477	0.989
	Robust Poisson	0.051	0.461	0.984
0.5	Log-Binomial	0.049	0.279	0.856
	Robust Poisson	0.050	0.275	0.842
0.7	Log-Binomial	0.045	0.256	0.825
	Robust Poisson	0.045	0.258	0.815

* Same simulations as in Table 1. Estimated size and power are the proportions of the 1,000 simulations which have a p-value less than or equal to 0.05. The log-binomial method used the COPY method approximation when needed. Wald tests were used for the Robust Poisson method, and likelihood ratio tests were used for the log-binomial method.
^† Size is the probability of concluding that the true slope is not zero when in fact it is zero, and power is the probability of concluding that the true slope is not zero when in fact it is not zero.

ISSN: 1471-2288