What are some of the different types of hypothesis tests and how do I choose which one to use?
Answer
Here’s a few common tests that are frequently used in an intro statistics class:

Paired ttest – Paired ttests 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 ttest to compare heart rates before and after study participants run a mile.

Ztest – This test also assumes all observations are independent. Always use the ztest when analyzing sample proportions. You can also use the ztest 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 ttest – 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 ztest or the ttest.

ChiSquare 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 chisquare test.