# Hypothesis Testing

In the previous section, we ran simulations where the sample mean changed from sample to sample, despite sampling from the same population. But how will we know if a sample mean we calculate is significantly different from a preconceived value or even a different sample? How will we know if a difference is variability in action, or if the measures are different? The answer lies in conducting a hypothesis test.

A **hypothesis test** is a statistical test that is designed to determine whether a statistic is significantly different from what we expect. Examples of hypothesis tests include checking to see whether the sample mean is significantly different from a pre-established standard or compare two different samples to see whether they are statistically different or the same.

## Parts of a Hypothesis Test

There are three main parts to any hypothesis test: the hypotheses, the test statistic, and the p-value. The *hypotheses* are what you are conducting the tests on...