Sample Size for Two-Sample Poisson Test

Plan the exposure and group sizes needed to compare two Poisson rates. Enter both expected rates, the allocation ratio, any overdispersion, and the desired alpha and power so you can see the exposure required per group.

Where it fits

• Incident rate comparisons between two treatments or sites
• Reliability tests across two production lines
• Safety monitoring with time-at-risk that differs by group

Parameters to provide

• Rates for group 1 and group 2
• Alpha, sidedness, and desired power
• Overdispersion setting and allocation ratio