what is the test for difference proportion what type of omnibus test would you use when you are testing proportional data why is a z test used instead of a t test why use z test why do we test for proportional data why use t-test or z test why use t and z tests why use a z test in omnibus tests why would i use a z test instead of a t test for proportional data? why use a t test instead of a z test why use a z test or t test when analyzing a proportion why use an omnibus test why use an omnibus test why would an omnibus test be used why use a z test why use a t test when testing a significant difference between two proportions why do we use a z test instead of a t test why should we use a z test rather than a t test why not use an omnibus test to test the difference between two proportions? why use a z test instead of a t test