Editing Biostatistics (section)

=== Power and statistical error ===

When testing a hypothesis, there are two types of statistic errors possible: [[Type I error]] and [[Type II error]]. 

* The type I error or [[False positives and false negatives|false positive]] is the incorrect rejection of a true null hypothesis
* The type II error or [[False positives and false negatives|false negative]] is the failure to reject a false [[null hypothesis]]. 

The [[significance level]] denoted by α is the type I error rate and should be chosen before performing the test. The type II error rate is denoted by β and [[Statistical power|statistical power of the test]] is 1 − β.