A researcher would like to determine whether regular doses of St. John's Wort have an effect on memory for college students. A group of 50 students is selected and each student is given a standardized memory test. Then each of the students takes a daily dose of St. John's Wort for 6 weeks. At the end of 6 weeks, the students are once again given a memory test. The researcher intends to compare the scores from the two tests whether there is any change in memory ability. - is the sample in the study. - is the population in the study.