Type I Error (α)
Rejecting H₀ when it is actually true — a "false alarm".
Also known as: Type I error, false positive, alpha error
A Type I error (α error, false positive) occurs when a test claims an effect that does not exist. Its probability is controlled by the significance level α.
- Practical example: a quality test raises an alarm about a production deviation that is not real — production is stopped needlessly
- Costs are usually visible: unnecessary rework, resources, lost trust in statistics
- Control by the choice of α and by corrections for multiple testing
See also
Used in
Sources
- Neyman, J. & Pearson, E. S. — On the Problem of the Most Efficient Tests, 1933