For 2sample Poisson rate, the hypotheses are as follows.
 Null hypothesis

H_{0}: λ_{1}– λ_{2} = d_{0} 
The difference between the population rates of two samples (λ_{1}– λ_{2}) equals the hypothesized difference (d_{0}). 
 Alternative hypothesis
 Select one of the following alternative hypotheses.
H_{1}: λ_{1}– λ_{2} ≠ d_{0} 
The difference between the population rates of two samples (λ_{1}– λ_{2}) is not equal to the hypothesized difference (d_{0}). 
H_{1}: λ_{1}– λ_{2} > d_{0} 
The difference between the population rates of two samples (λ_{1}– λ_{2}) is greater than the hypothesized difference (d_{0}). 
H_{1}: λ_{1}– λ_{2} < d_{0} 
The difference between the population rates of two samples (λ_{1}– λ_{2}) is less than the hypothesized difference (d_{0}). 