What is a type 1 error? Explain why psychologists use the significance level of 0.05 in research (3 marks)

A type 1 error arises when after an experiment, the null hypothesis is rejected even when it is true and the alternative hypothesis is accepted. This can be referred to as a false positive as a significant correlation/difference is found when it does not exist. *To help remember this in an exam, think of a real life example such as a false positive pregnancy test. The pregnancy test would claim that an individual was pregnant even if they weren't.
Psychologists use the significance level of 0.05 in research as it best balances the risk of making type 1 and type 2 errors. *This would need to be a clear statement in the exam in order to get the mark.