D Question 6 3 pts The difference between a sample mean and its parameter is called: sampling error a biased statistic pooled variance The standard error of means (SEM) D Question 7 3 pts Which of the following research scenarios uses a two samples independent-measures t test? Examine the difference in self-esteem between student athletes and non-athletes. O Evaluate the effectiveness of a pain reliever by measuring how much pain is reduced after taking the medication in a single group of people who rated pain, then took the drug and rated pain a second time. O Test the effectiveness of a cholesterol medication by comparing cholesterol levels before and after the medication is administered to a single group. O Calculating the z score for the highest X in the data set. Question 8 3 pts When a random sample of participants is selected from a population, the sample mean is not expected to be exactly equal to the population mean. On average, the size of the difference between the sample mean and the population mean is predicted by the standard error of means (SEM) O the mean of the population the sample variance the standard deviation of the population