Stata Help

Binomial Probability Test

When you have variables with values like yes/no or fail/succeed, you're working with a binomial variable. If you expect a certain distribution of that binomial variable, you can test it using the bitest command. This may sound confusing in the abstract, so lets work with an example:

Say I am curious if Reed's population is better at spatial reasoning than a general US sample - a completely made-up meta-analysis reveals that 38% of the US population passes spatial reasoning tasks. I subject a random sample of 50 Reed students to the same test. The variable is called "spatial" and the command to see if Reed passes the test more often than the general US population would be bitest spatial=.38

The result of my test is highly significant whether I use the better performance hypothesis Pr (> = 40) or the two-tail test Pr(k <= 1 or k >= 40). This means that more Reedies succeed at a spatial reasoning test than the general poluation.