Statistics and Probability Dictionary

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Type II Error

Two types of errors can result from a decision rule .

  • Type I error. A Type I error occurs when the researcher rejects a null hypothesis when it is true. The probability of committing a Type I error is called the significance level , and is often denoted by α.

  • Type II error. A Type II error occurs when the researcher accepts a null hypothesis that is false. The probability of committing a Type II error is called Beta, and is often denoted by β. The probability of not committing a Type II error is called the Power of the test.
See also:   Statistics Tutorial: Hypothesis Tests