Web Calculator Exercise 5
ANOVAs
1.
A
researcher is interested in comparing the effectiveness of three different
kinds of therapy for anger problems. Eight participants are randomly assigned
to three treatment conditions: Cognitive Therapy (CT), CognitiveBehavioral
Therapy (CBT), and Interpersonal Therapy (IT). All participants complete the
weekly treatment for 8 weeks. Participants take an anger test before and after
the 8week treatments. Each participant’s difference score (= anger score after
the treatment minus (–) anger score before the treatment) is shown in the
following table. The three therapists in this experiment have equal educational
levels and clinical experiences.
CT

CBT

IT

3

5

7

4

4

8

4

6

9

4

6

10

3

5

6

8

4

7

6

9

11

2

7

10

a.
What
statistical test should be used to analyze the data?
b.
Identify
H_{0} and H_{a} for this study.
c.
Conduct
the appropriate analysis.
d.
Should
H_{0} be rejected? What should the researcher conclude?
2.
A
teacher is interested in comparing the effects of three different types of
rehearsal methods (Rote rehearsal, Imagery, and Story) on number of words
recalled. Participants are randomly assigned into three different groups. In
each group, participants are asked to study a list of words using the assigned
method. The following table shows the result.
Rote rehearsal

Imagery

Story

5

5

7

5

4

6

4

6

8

6

7

9

5

7

6

4

6

9

3

8

8

5

5

10

6

7

9

a.
What
statistical test should be used to analyze the data?
b.
Identify
H_{0} and H_{a} for this study.
c.
Conduct
the appropriate analysis.
d.
Should
H_{0} be rejected? What should the researcher conclude?
e.
If
there is a significant difference, conduct the post hoc test.
3.
A
professor is interested in whether there is a difference in counseling
students’ statistics competency scores among 1) those who have never taken any
statistics course, 2) those who have only taken an undergraduate statistics
course, 3) those who have taken COUN 503, and 4) those who have taken an advanced
statistic course while working on a Ph. D. The professor gathers information
from a random sample of students and obtains the statistics competency scores. The
scores are normally distributed.
1)

2)

3)

4)

7

11

13

15

6

11

14

14

8

10

15

15

5

12

12

15

4

13

13

10

4

15

13

15

a.
What
statistical test should be used to analyze these data?
b.
Identify
H_{0} and H_{a} for this study.
c.
Conduct
the appropriate analysis.
d.
Should
H_{0} be rejected? What should the researcher conclude?