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Type I Error Calculator

Formula

To calculate the Probability of a Type I Error ( $P(\text{Type I Error})$ ):

$P(\text{Type I Error}) = \alpha$

Where:

$\alpha$ is the Significance Level

What is a Type I Error?

A Type I Error, also known as a “false positive,” occurs when a statistical hypothesis test incorrectly rejects a true null hypothesis. This means that the test indicates that there is an effect or a difference when in fact there is none. The significance level ( $\alpha$ ) is the probability of making a Type I Error, and it is set by the researcher before conducting the test.

Example Calculation 1

Let's assume the following value:

Significance Level ( $\alpha$ ) = 0.05

Using the formula:

$P(\text{Type I Error}) = 0.05$

The Probability of a Type I Error is 0.05 or 5%.

Example Calculation 2

Let's assume the following value:

Significance Level ( $\alpha$ ) = 0.01

Using the formula:

$P(\text{Type I Error}) = 0.01$

The Probability of a Type I Error is 0.01 or 1%.