Statistics Homework Help?

1. Find the critical value(s) of t that would be used for the following independent measures t-test(assume that the null hypothesis is population mean 1 = population mean 2 with an alpha level
of 0.05. What would the critical value be for n1=21, n2=21?
2. For the previous question in which you had an independent samples t-test with n1=21, n2=21,
what would be your decision regarding the null hypothesis if your obtained t value (tobt) was 1.97?
3. Find the critical value(s) of t that would be used for the following independent measures t-test
(assume that the null hypothesis is population mean 1 = population mean 2 with an alpha level
of 0.05. What would the critical value be for n1=8, n2=12?
4. For the previous question in which you had an independent samples t-test with n1=8, n2=12,
what would be your decision regarding the null hypothesis if your obtained t value (tobt) was 1.69?
5. A researcher is interested in understanding the effect of marijuana on memory
enhancement. She would like to have 20 memory scores in each of the two conditions (small
dose and large dose). If she was using a dependent samples design, how many total subjects
would she need?
6. A researcher is interested in understanding the effect of marijuana on memory
enhancement. She would like to have 20 memory scores in each of the two conditions (small
dose and large dose). If she was using a matched subjects design, how many total subjects
would she need?
7. A researcher is interested in understanding the effect of marijuana on memory
enhancement. She would like to have 20 memory scores in each of the two conditions (small
dose and large dose). If she was using an independent samples design, how many total subjects
would she need?
8. A professor is interested in the effect of frequent testing on retention of course material. In one
of the professor’s sections, students are given quizzes each week. In another section, students
take only two tests over the course of the semester. End-of-semester averages are compared
between the groups and the value for the pooled variance was 7.5. Do the data indicate that
frequent testing improves performance? Assume alpha=.05 and show all 5 steps of your
hypothesis test. Then, determine the effect size using Cohen’s d. Frequent testing group: M =
72, s = 2.7, n = 15 Two exams group: M = 68, s = 2.8, n = 15
9. Relaxation training may help treat anxiety. In an experiment, seven participants are
administered an anxiety survey before and after relaxation training. Anxiety
scores dropped 2.29 points after the training (SD = 2.93). The value for tobt was 2.07. Do these
data indicate a significant change in anxiety? Assume alpha = .05 and show all 5 steps of your
hypothesis test. Then, determine effect size using r2. NOTE: Not everything will need to be
calculated based on the information provided here.