Which statement best describes a type II error?

A type II error occurs when a researcher fails to reject a null hypothesis that is actually false. This means that even though there is sufficient evidence to suggest that an effect or difference exists, the researcher mistakenly concludes that it does not. In practice, this can lead to missed opportunities for discovery or an underestimation of the impact that a variable may have.

The chosen statement accurately conveys this concept by highlighting the misinterpretation of failing to reject a null hypothesis that should have been rejected. Such errors can occur in various research settings, particularly when the sample size is small or the effect size is subtle.

Understanding type II errors is crucial in research design as it underscores the importance of selecting appropriate sample sizes and power analyses to reduce the likelihood of making such an error.