A DOSM is the average of the means of different samples taken from the same population. This is used as a comparison distribution when performing hypothesis testing because you cannot compare the scores of a sample to the average of the total population. This would be comparing 2 different things. They aren’t on the same scale. A DOSM is used because it is on the same scale as the average from a sample. You’re comparing data from a sample to data from samples instead of data from a sample to data from population. More test answers on https://studyhippo.com/multiple-choice-stats-practice/