ABSTRACT
Researchers can never accept their hypotheses unequivocally. They have to evaluate how likely the results they achieved were to have occurred if the Null Hypothesis were true. On this basis, they can choose whether or not to reject the Null Hypothesis. There is a convention that if the result has a probability of occurring, if the Null Hypothesis were true, of .05 or less, then the result is described as statistically significant and the Null Hypothesis can be rejected. This probability level has been chosen as the best value for avoiding both a Type I error – rejecting the Null Hypothesis when it is true – and a Type II error – failing to reject the Null Hypothesis when it is false.
