The probability of committing a Type II error is called what, according to Cohen (1992) guidelines?

• A. Type I error
• B. β-level
• C. Type II error
• D. P-value

Answer: (B)

The probability of committing a Type II error is called the beta level. In hypothesis testing, a Type II error happens when you fail to reject the null hypothesis even though it is false. The beta level, denoted beta, represents how often that mistake occurs. Cohen (1992) uses this term to frame power analysis, since power equals 1 minus beta—the probability of correctly detecting a real effect. By contrast, a Type I error is the change of falsely rejecting a true null (alpha), and the P-value is the observed probability, under the null, of obtaining a result as or more extreme than what was observed.