Which description matches a Type II error?

Which description matches a Type II error?

• A. Failing to reject the null when it is true.
• B. Rejecting the null when it is true.
• C. Failing to reject the null when it is false.
• D. Rejecting the null when it is false.

Answer: (C)

Type II error happens when the test fails to detect an actual effect; you don’t reject the null even though it is false. In practice, there’s a real difference or effect, but the evidence isn’t strong enough to override the null hypothesis, so you conclude there isn’t an effect. This risk is higher with small samples or small true effects, and it can be reduced by increasing sample size or the study’s power. The description that matches this is: failing to reject the null when it is false. Rejecting the null when it is true describes a Type I error, rejecting the null when it is false is the correct decision, and failing to reject the null when it is true is simply a correct decision.

Type II error happens when the test fails to detect an actual effect; you don’t reject the null even though it is false. In practice, there’s a real difference or effect, but the evidence isn’t strong enough to override the null hypothesis, so you conclude there isn’t an effect. This risk is higher with small samples or small true effects, and it can be reduced by increasing sample size or the study’s power.

The description that matches this is: failing to reject the null when it is false. Rejecting the null when it is true describes a Type I error, rejecting the null when it is false is the correct decision, and failing to reject the null when it is true is simply a correct decision.