Statistics – Type I and Type II Errors

Errors in Statistical Decision-Making

Type I Error — \(\alpha\)

Rejecting \(H_0\) when it is true

= False Positive = "false alarm"

Probability of this error = \(\alpha\) = significance level

Type II Error — \(\beta\)

Failing to reject \(H_0\) when it is false

= False Negative = "missed detection"

Decision table

\(H_0\) true\(H_0\) false
Reject \(H_0\)Type I Error (\(\alpha\))Correct decision
Fail to reject \(H_0\)Correct decisionType II Error (\(\beta\))