A counseling psychologist developing a technique to reduce procrastination has students time their procrastination for a week and uses this as a pretest measure of procrastination. Students then attend a workshop in which they are instructed to do a specific warm-up exercise for studying by focusing on a pleasant activity. Students again time their procrastination for a week, and the time from this second week is the posttest measure.
-If the psychologist wants to see if there is a change (increase or decrease)in procrastination by 10 of the students who attended his workshop using the .05 significance level,the cutoff t score(s)would be
A)-.62,0,+2.62
B)+2.262
C)-2.262,0
D)-2.262,+2.262

Question

Quizplus · Accepted Answer

Since the psychologist wants to see if there is a change in procrastination, a paired samples t-test should be used. The null hypothesis would be that there is no difference in procrastination before and after the workshop (mu d = 0), while the alternative hypothesis would be that there is a change (mu d ≠ 0).

Since the sample size is less than 30 and the population variance is unknown, the t-distribution should be used. With a significance level of .05 and 10 degrees of freedom (n-1), the cutoff t-score(s) would be -2.262 and +2.262. Therefore, the best choice(s) is D -2.262 and +2.262.

A Counseling Psychologist Developing a Technique to Reduce Procrastination Has