+A **Type II error** occurs when a statistical test fails to reject a [Null Hypothesis](/wiki/null_hypothesis) that is, in reality, false. It means missing a true effect or difference, leading to a [False Negative](/wiki/false_negative). This oversight diminishes a study's intended strength.
+## See also
+- [Type I Error](/wiki/type_i_error)
+- [Hypothesis Testing](/wiki/hypothesis_testing)
+- [Statistical Power](/wiki/statistical_power)