Q. What are some of the different types of hypothesis tests and how do I choose which one to use?
Here’s a few common tests that are frequently used in an intro statistics class:
Paired t-test – Paired t-tests are used when you don’t have independent observations. In most cases, this takes the form of a before/after study. For example, you could use a paired t-test to compare heart rates before and after study participants run a mile.
Z-test – This test also assumes all observations are independent. Always use the z-test when analyzing sample proportions. You can also use the z-test to compare sample means when the sample size is greater than 30, or when the sample size is less than 30 but the population is normally distributed, and the population standard deviation is known.
Independent samples t-test – This test assumes all observations are independent. It is used to compare sample means in cases where there are less than 30 observations, the population is normally distributed, and the population standard deviation is unknown. If the sample size is small and not normally distributed, we cannot use the z-test or the t-test.
Chi-Square test – This test differs from the three tests listed above because it is only used to evaluate categorical variables. Click link to learn more about when to use a chi-square test.