Statistical inference
(Redirected from Statistical hypothesis testing)
Hypotheses
edit- Null Hypothesis (H0): No differences or effect
- Alternative Hypothesis (H1): Differences or effect
Decisions
editWhen a hypothesis is tested, a conclusion is drawn, based on sample data; either:
- Do not reject H0, p is not significant (i.e. not below the critical alpha (α))
- Reject H0, p is significant (i.e., below the critical α)
Correct decisions
edit- Do not reject H0: Correctly retain H0 when there is no real difference/effect in the population
- Reject H0 (Power): Correctly reject H0 when there is a real difference/effect in the population
Incorrect decisions: Type I and II errors
editHowever, when we fail to reject or reject H0, we risk making errors:
- Type I error: Incorrectly reject H0 (i.e., there is no difference/effect in the population)
- Type II error: Incorrectly fail to reject H0 (i.e., there is a difference/effect in the population)
Decision-making table
editCells represent:
- Correct acceptance of H0
- Power (correct rejection of H0) = 1-β
- Type I error (false rejection of H0) = α
- Type II error (false acceptance of H0) = β
Traditional emphasis has been too much on Type I errors and not enough on Type II error – balance needed.