suppose you always reject the null hypothesis regardless of

suppose you always reject the null hypothesis, regardless of any sample evidence. a. what is the probability of type 2 error? b. why is this a bad policy?

Solution

Since a Type II error occurs when you fail to reject the null hypothesis when it is, in fact, false, always rejecting the null would amount to never failing to reject the null. This would mean that a Type II error could never occur. The probability of a Type II error would then be 0.

The chance of making a Type I error would then be uncontrolled. You could be making anywhere from 0% Type I errors to 100% Type I errors, depending on the null hypotheses and the statistics involved,
This is bad because your probability of a type 1 error (incorrectly rejecting the null hypothesis and instead going with the alternative hypothesis) will be unreasonably high.