This statlet tests hypotheses about the rate parameters of two Poisson distributions. The tabs are:
To use this statlet, enter information about your data:
Sample labels - names to be displayed on the output.
Sample sizes - the sizes of the samples.
Sample rates - the observed sample rates.
This tab shows the result of a hypothesis test concerning the difference between the rates:
It shows:
Summary statistics.
A confidence interval for the difference between the rates.
The result of a hypothesis test run to test a hypothesis about the difference between the rates.
Use the Options button to specify the hypotheses to be tested. If the P-value is less than the alpha risk which you specify, you should reject the null hypothesis at the corresponding significance level.
Enter:
Null hypothesis - the value of the difference between the rates specified by the null hypothesis.
Alt. Hypothesis - select a two-sided test (~=) or a one-sided test.
Alpha - the probability of a Type I error, which is a situation where a true null hypothesis is incorrectly rejected. Typical values for alpha are 10%, 5%, and 1%. The confidence interval is also affected by this setting and uses a confidence level equal to (100-alpha)%.
This tab shows the power curve for the hypothesis test:
The power curve shows the probability of rejecting the null hypothesis as a function of the true difference between the population rates.
Same as previous tab.