There are two basic types of errors that can occur in hypothesis testing:
- Type A or 1 Error: The null hypothesis is correct, but is incorrectly rejected.
- Type B or 2 Error: The null hypothesis is incorrect, but is not rejected.
The traditional way of explaining testing errors is with a table like the one shown below:
Typically, we’re more worried about Type A errors than Type B – rejecting a hypothesis that is not actually incorrect.
Need more explanation? Khan Academy’s video does a good job of walking through Type A (or Type 1) errors:
ASQ Six Sigma Green Belt Errors in Hypothesis Testing Questions:
Question: When an inspection process rejects conforming product, what type of error is being made?
Question: Which of the following terms is used to describe the risk of a type I error in a hypothesis test?
(B) Confidence level
(C) Level of significance
(D) Beta risk
Question: Which of the following is a commonly accepted level for alpha risk?