WEEK 6 – EXERCISES Enter your answers in the spaces provided. Save the file using your last name as the beginning of the file name (e.g., ruf_week6_exercises) and submit via “Assignments.” When appropriate, show your work . You can do the work by hand, scan/take a digital picture, and attach that file with your work. 1 . A psychotherapist studied whether his clients self-disclosed more while sitting in an easy chair or lying down on a couch. All clients had previously agreed to allow the sessions to be videotaped for research purposes. The therapist randomly assigned 10 clients to each condition. The third session for each client was videotaped and an independent observer counted the clients’ disclosures. The therapist reported that “clients made more disclosures when sitting in easy chairs ( M = 18.20) than when lying down on a couch ( M = 14.31), t (18) = 2.84, p < .05, two-tailed.” Explain these results to a person who understands the t test for a single sample but knows nothing about the t test for independent means. 2. A researcher compared the adjustment of adolescents who had been raised in homes that were either very structured or unstructured. Thirty adolescents from each type of family completed an adjustment inventory. The results are reported in the table below. Explain these results to a person who understands the t test for a single sample but knows nothing about the t test for independent means. Means on Four Adjustment Scales for Adolescents from Structured versus Unstructured Homes Scale Structured Homes Unstructured Homes t Social Maturity 106.82 113.94 –1.07 School Adjustment 116.31 107.22 2.03* Identity Development 89.48 94.32 1.93* Intimacy Development 102.25 104.33 .32 ______________________ * p < .05 3. Do men with higher levels of a particular hormone show higher levels of assertiveness? Levels of this hormone were tested in 100 men. The top 10 and the bottom 10 were selected for the study. All participants took part in a laboratory simulation in which they were asked to role-play a person picking his car up from a mechanic’s shop. The simulation was videotaped and later judged by independent raters on each of four types of assertive statements made by the participant. The results are shown in the table below. Explain these results to a person who fully understands the t test for a single sample but knows nothing about the t test for independent means. Mean Number of Assertive Statements Type of Assertive Statement Group 1 2 3 4 Men with High Levels 2.14 1.16 3.83 0.14 Men with Low Levels 1.21 1.32 2.33 0.38 t 3.81** 0.89 2.03* 0.58 ______________________ * p < .05; ** p < 0.1 4. A manager of a small store wanted to discourage shoplifters by putting signs around the store saying “Shoplifting is a crime!” However, he wanted to make sure this would not result in customers buying less. To test this, he displayed the signs every other W.

1. WEEK 6 – EXERCISES
Enter your answers in the spaces provided. Save the file using
your last name as the beginning of the file name (e.g.,
ruf_week6_exercises) and submit via “Assignments.” When
appropriate,
show your work
. You can do the work by hand, scan/take a digital picture, and
attach that file with your work.
1
.
A psychotherapist studied whether his clients self-disclosed
more while sitting in an easy chair or lying down on a couch.
All clients had previously agreed to allow the sessions to be
videotaped for research purposes. The therapist randomly
assigned 10 clients to each condition. The third session for each
client was videotaped and an independent observer counted the
clients’ disclosures. The therapist reported that “clients made
more disclosures when sitting in easy chairs (
M
= 18.20) than when lying down on a couch (
M
= 14.31),
t
(18) = 2.84,
p

2. < .05, two-tailed.” Explain these results to a person who
understands the
t
test for a single sample but knows nothing about the
t
test for independent means.
2.
A researcher compared the adjustment of adolescents who had
been raised in homes that were either very structured or
unstructured. Thirty adolescents from each type of family
completed an adjustment inventory. The results are reported in
the table below. Explain these results to a person who
understands the
t
test for a single sample but knows nothing about the
t
test for independent means.
Means on Four Adjustment Scales for
Adolescents from Structured versus Unstructured Homes
Scale
Structured Homes
Unstructured Homes
t

3. Social Maturity
106.82
113.94
–1.07
School Adjustment
116.31
107.22
2.03*
Identity Development
89.48
94.32
1.93*
Intimacy Development
102.25
104.33
.32
______________________
*
p
< .05
3.
Do men with higher levels of a particular hormone show higher
levels of assertiveness? Levels of this hormone were tested in
100 men. The top 10 and the bottom 10 were selected for the
study. All participants took part in a laboratory simulation in
which they were asked to role-play a person picking his car up
from a mechanic’s shop. The simulation was videotaped and
later judged by independent raters on each of four types of

4. assertive statements made by the participant. The results are
shown in the table below. Explain these results to a person who
fully understands the
t
test for a single sample but knows nothing about the
t
test for independent means.
Mean Number of Assertive Statements
Type of Assertive Statement
Group
1
2
3
4
Men with High Levels
2.14
1.16
3.83
0.14
Men with Low Levels
1.21
1.32
2.33
0.38
t

5. 3.81**
0.89
2.03*
0.58
______________________
*
p
< .05;
**
p
< 0.1
4.
A manager of a small store wanted to discourage shoplifters by
putting signs around the store saying “Shoplifting is a crime!”
However, he wanted to make sure this would not result in
customers buying less. To test this, he displayed the signs every
other Wednesday for 8 weeks, for a total of 4 days displayed.
He recorded the store’s sales for those four Wednesdays and
then recorded the store’s sales for the four alternate

6. Wednesdays, when the signs were not displayed. On the
Wednesdays with the sign, the sales were 83, 73, 81, and 79. On
the Wednesdays without the sign, sales were 84, 90, 82, and 84.
Do these results suggest that customers buy less when the signs
are displayed? (Use the .05 significance level.)
a.
Use the five steps of hypothesis testing.
b.
Sketch the distribution involved.
c.
Figure the effect size.
d.
Explain what you did to a person who is familiar with the
t
test for a single sample but is unfamiliar with the
t
test for independent means.
SPSS ASSIGNMENT #6

7. The t Test for Independent Samples
SPSS instructions t
o run the t Test for Independent Samples: (For more details,
check the links provided under “Course Materials” in the
Course Overview Folder (under Lessons).
Once you have entered the data, click on
Analyze
, then on
Compare Means
, and then click on
Independent-Samples T Test
…
A dialog box will appear, with your variables (student,
condition, score) on the left. Your options are (a) move one or
more variables into the “Test Variable(s)” box to select your
dependent variables(s) and (b) move one of your variables into
the “Grouping Variable” box to select the independent variables
(or identify the groups to be compared).
Make “?” the dependent variable by moving it to the “Test
Variable(s)” box. Then make “?” your independent variable by
moving it to the “Grouping Variable” box.

8. Now, the “Define Groups” button is functioning, click on
Define Groups
and another dialog box appears. Here you must specify the two
values of the condition variable that represent the two groups
you are comparing.
Click
in the box next to Group 1 and type the number 1, then
click
in the box next to Group 2 and type the number 2.
Now you can click
Continue
to return to the “Independent-Samples T Test” dialog box, and
click on
OK
to run the analysis.
Six months after an industrial accident, a researcher has been
asked to compare the job satisfaction of employees who
participated in counseling sessions with the satisfaction of
employees who chose not to participate.
The scores on a job satisfaction inventory for both groups are
listed in the table below.
Use the five steps of hypothesis testing to determine whether
the job satisfaction scores of the group that participated in
counseling are statistically higher than the scores of employees
who did not participate in counseling at the .01 level of
significance.

9. In Step 2, show all calculations.
As part of Step 5, indicate whether the researcher should
recommend counseling as a method to improve job satisfaction
following industrial accidents based on evaluation of the null
hypothesis and calculate the effect size.
PARTICIPATED IN COUNSELING
DID NOT PARTICIPATE IN COUNSELING
36
37
39
35
40
36
36
33
38
30
35
38
37
39
39
35
42
32

12. A researcher is interest in the effect of exercise on the
perceptions of well-being among older. The researcher
identified 30 residents of a retirement community and divided
them into groups of 15 residents. Both groups were encouraged
to walk at least 20 minutes per day. One group, however, also
participated in a structured exercise program that emphasized
flexibility. After 6 weeks, the behavioral scientist mailed
questionnaires to the 30 residents. Responses to an item asking
residents to rate their perceptions of their health on a 10-point
scale on which 1 indicated “very unhealthy” and 10 indicated
“very healthy” are presented in the table that follows.
Use the five steps of hypothesis testing to determine whether
the observed differences in health ratings of the two groups are
statistically significant at the .05 level of significance.
In Step 2, show all calculations.
As part of Step 5, indicate whether the researcher should
recommend exercise as a method to improve perceptions of
health among older adults based on evaluation of the null
hypothesis and calculate the effect size.
WALKING AND FLEXIBILITY
WALKING ONLY
5
2
6
3
6
4
4
3
9
6

13. 4
7
7
7
9
6
6
7
7
4
9
6
7
4
9
8
Week 6 SPSS Tips
The t Test for Independent Samples
The instructions tell you to use three variables: student,
condition, and score.
What you are given is a chart which shows scores for two
groups. In the example "student" would be something like a

14. student name or ID which you would have; either leave this
blank or make up something to illustrate the example. Then
"condition" is a group identifier: for the SPSS program use "1"
for the first group and "2" for the second group. Then the
"score" is the actual data you are given. The t-Test will ask for
the grouping variable which is the "1" or "2" identifying the
group.
PARTICIPATED IN COUNSELING
DID NOT PARTICIPATE IN COUNSELING
36
37
39
35
40
36
36
33
38
30
35
38
37
39
39
35
42
32
The assignment includes the table I copied above.
Your data input will have a column which identifies the group
("1" for Participated in Counseling and then "2" for Did not
Participate in Counseling). The column next to it will be the
score such as:
1 36
1 39
1 40
1 36

15. 1 38
1 35
1 37
1 39
1 42
2 37
2 35
2 36 and so forth
When interpreting the results of an independent t-Test you need
to know how to interpret the results of the Levene’s Test for
Equality of Variances. These results appear in the first two
columns of the “Independent Samples Test” output under the
“Levene’s Test for Equality of Variances” heading.
The results of this test determine which line of the SPSS output
you are using. That is either, “Equal variance assumed” or
“Equal variances not assumed.” If the Levene’s Test results are
significant (that is significance level below .05) you use the
second line of the data for equal variances not assumed. If the
Levene’s Test results are not significant (that is significance
level above .05) you use the first line of the data for equal
variances assumed. Once you know which line to use, then look
across straight across on the same line for the results under “t-
test for Equality of Means.” Only use the results on the
appropriate line.
Degrees of freedom for an Independent Sample Test is
calculated as:

16. Number in group 1 plus the Number in group 2 minus 2
Note that this formula allows for a difference in the size of the
groups which is acceptable when using an independent t-Test.
While it is important to be able to determine significance by
using the t score and degrees of freedom on the appropriate
table, in practice we use the significance level we obtain from
the SPSS output. This also allows us to see how close we were
to significance and help us determine if our results—significant
or not significant—are of interest to us.