Question

Criminology Statistics

Chapter 5: The Sampling Distribution and Estimation Procedures

(4) What does alpha represent? Where (generally) does it come from? Do we want a large alpha or a small one? Why?

Answer 1

Alpha level is the probability of rejecting the null hypothesis when the null hypothesis is true.

It’s the probability of making a wrong decision.

For example, selecting an Alpha 5% signifies that there is a 5% chance of incorrectly rejecting the Null hypothesis.

Reducing the alpha level from 0.05 to 0.01 reduces the chance of Type I error (alpha).

The advantage of 0.01 alpha level over a 0.05 alpha level is there is less of a chance you made a Type I error. You usually are able to use an alpha level of 0.01 when you have a very large sample size or where a Type I error has very serious consequences.