Beta risk (β) is the risk that a decision will be made that a part is not defective when it really is. In other words, when the decision is made that a difference does not exist when there actually is. Or when the data on a control chart indicates the process is in control but in reality the process is out of control. Beta risk is also called False Negative, Type II Error, or “Consumer’s” Risk.
Power = 1 – Beta risk = 1 – β
The Power is the probability of correctly rejecting the Null Hypothesis.
The Null Hypothesis is technically never proven true. It is “failed to reject” or “rejected”.
“Failed to reject” does not mean accept the null hypothesis since it is established only to be proven false by testing the sample of data.
If the power desired is 90%, then the beta risk is 10%. There is a 10% chance that the decision will be made that the part is not defective when in reality it is defective.
For example, the risk of passing parts that are actually defective. The “Consumer” is taking a risk of due to the Producer making an incorrect decision and putting these bad parts out for the Consumer (or customer) to use or purchase, hence it being also known as “Consumer’s Risk”.
Alpha and Beta Risks. (n.d.). Retrieved June 22, 2021, from https://www.six-sigma-material.com/Alpha-and-Beta-Risks.html