Research Methods: Type 1 and Type 2 Errors

Type 1 and Type 2 Errors

• In science, results are never certain.
• Science deals with probabilities and makes judgements about what probability to accept or reject as significant.
• A significant result is one where there is a low probability that chance factors were responsible for the observed difference, correlation or association between variables tested.

Levels of Significance

• The role of statistical tests is to find out how probable it is that what we have found in our sample accurately reflects what happens in the population.
• Hypothesis testing can be viewed as a competition betwen the experimental hypothesis and the null hypothesis.
• Psychologists generally use a level of significance of P<0.05.
• P stands for probability that chance factors were responsible for results.
• This means probability of the results occurring by chance is less than or…