Week 5 Independent t Test Exercises

Answer the questions below for Part I II and III. Make sure to create the table if asked and do not submit SPSS output as your answer. If you have any questions, please email your instructor. Don’t forget to save the document as instructed in the assignment submission directs. You do not have to submit a title page or reference list for this assignment. No citations are required for your submission.

Part I

The hypothesis being tested is: Women who are working will have a lower level of depression as compared to women who are not working.

Using Polit2SetC SPSS dataset, which contains a number of mental health variables, determine if the above hypothesis is true.

Follow these steps when using SPSS:

1. Open Polit2SetC dataset.

2. Click Analyze then click Compare Means, then Independent Sample T-test.

3. Move the Dependent Variable (CES_D Score “cesd”) in the area labelled Test Variable.

4. Move the Independent Variable (Currently Employed “worknow”) into the area labelled Grouping Variable. The worknow variable is coded as (0= those women who do not work and 1= those women who are working). Click on Define Groups in group 1 box type 0 and in group 2 box type 1. Click Continue.

5. Click continue and then click OK.

6. Check your answers to the Week 5 t Test Excercises SPSS Output.

Assignment: Through analysis of the data answer the questions below with your findings from this t-test.

1. How many women were employed versus not employed in the sample?

2. What is the total sample size?

3. What are the mean and standard deviation for the CES-D scores for each group?

4. Interpret the Levene’s statistic. (Hint: Is the assumption of homogeneity of variance met? Are equal variances assumed or not assumed?) Why?

5. What is the value of the t-statistic, number of degrees of freedom and the p-value?

6. Does the data support the hypothesis? Why or why not?

Part II

Hypothesis: Women who reported depression scores in wave 1 and wave 2 of the study did not have a significant difference in their level of depression.

Using Polit2SetC SPSS dataset, determine if the above hypothesis is true.

Follow these steps when using SPSS:
1. Open Polit2SetC dataset.

2. Click Analyze then click Compare Means, then Paired Samples T-test.

3. First click on CES-D Score (cesd) and move it into the box labelled Paired Variables (in the rectangle for Pair 1 of Variable 1 and then click on CESD Score, Wave 1 (cesdwav1) and move it into the Paired Variables box (in the rectangle next to CES-D Score, pair 1, variable 2).

4. Click continue and then click OK.

5. Check your answers to the Week 5 t Test Excercises SPSS Output

Assignment: Through analysis of the data and answer the questions below for the findings from this t-test.

1. What is the total sample size?

2. What are the mean and the standard deviation of the CES-D scores at wave 1 and wave 2?

3. What is the mean difference between the two time periods?

4. What is the value of the t-statistic, number of degrees of freedom and the p-value(sig)?

5. Does the data support the hypothesis? Why or why not?

Part III

Using Polit2SetC dataset, run independent groups t-tests for three outcomes. The outcome variables are CES-D Score (cesd), SF12: Physical Health Component Score, standardized (sf12phys) and SF12: Mental Health Component Score, standardized (sf12ment).

Follow these steps when using SPSS:
1. Open Polit2SetC dataset.
2. Click Analyze then click Compare Means, then Independent Sample T-test.

3. Move the Dependent Variables (CES_D Score “cesd”, SF12: Physical Health Component Score, standardized (sf12phys), and SF12: Mental Health Component Score, standardized (sf12ment) ) in the area labelled Test Variable.

4. Move the Independent Variable (Educational Attainment “educatn”) into the area labelled Grouping Variable. The educatn variable is coded as (1= no high school credential and 2=diploma or GED). Click on Define Groups in group 1 box type 1 and in group 2 box type 2. Click Continue.

5. Click continue and then click OK.

6. Check your answers to the Week 5 t Test Excercises SPSS Output

Assignment: Create a table to present your results, use the table 6.3 in Chapter 6 in your book as a model. Write one or two paragraphs explaining and summarizing your results. Do not submit the SPSS output that is provided.

Week

5 t Test Exercises SPSS Output

Independent t test 

Group Statistics

Currently employed? N Mean Std. Deviation Std. Error

Mean

CES-D

Score

dimension1

No 524 20.8965 12.46425 .54450

Yes 436 15.8239 10.13655 .48545

Independent Samples Test

Levene’s Test

for Equality of

Variances t-test for Equality of Means

F Sig.

t df

Sig. (2-

tailed)

Mean

Difference

Std. Error

Difference

95% Confidence

Interval of the

Difference

Lower Upper

CES-D

Score

Equal variances

assumed

23.615 .000 6.825 958 .000 5.07264 .74326 3.61404 6.53124

Equal variances not

assumed
6.954 957.514 .000 5.07264 .72949 3.64107 6.50421

Dependent t test 

Paired Samples Statistics

Mean N Std. Deviation Std. Error Mean
Pair 1 CES-D Score 18.5516 157 11.87462 .94770

CESD Score, Wave 1 17.8344 157 11.49908 .91773

Paired Samples Correlations

N Correlation Sig.
Pair 1 CES-D Score & CESD

Score, Wave 1

157 .412 .000

Paired Samples Test

Paired Differences

t df
Sig. (2-

tailed) Mean

Std.

Deviation

Std. Error
Mean

95% Confidence Interval of

the Difference

Lower Upper

Pair 1 CES-D Score –

CESD Score, Wave 1

.71718 12.67921 1.01191 -1.28164 2.71599 .709 156 .480

Independent t test with 3 outcome variables 

Group Statistics
Educational attainment N Mean Std. Deviation Std. Error Mean
CES-D Score No high school diploma 453 20.1408 11.49986 .54031

Diploma or GED 475 17.5931 11.72389 .53793

SF12: Physical

Health

Component

Score,

standardized

No high school diploma 421 44.03546 10.781420 .525454

Diploma or GED 440 46.27713 10.597265 .505205

SF12: Mental Health

Component Score,
standardized

No high school diploma 421 45.70217 10.693544 .521171

Diploma or GED 440 47.48328 10.895127 .519405

Independent Samples Test

Levene’s Test
for Equality of
Variances t-test for Equality of Means

F Sig. t df

Sig. (2-
tailed)
Mean
Difference
Std. Error
Difference
95% Confidence
Interval of the
Difference
Lower Upper

CES-D Score Equal variances

assumed

.228 .633 3.340 926 .001 2.54776 .76278 1.05078 4.04474

Equal variances

not assumed
3.342 925.265 .001 2.54776 .76243 1.05146 4.04406

SF12: Physical

Health

Component

Score,
standardized
Equal variances
assumed

1.106 .293 -3.076 859 .002 -2.241671 .728649 -3.671812 -.811529

Equal variances

not assumed
-3.075 855.772 .002 -2.241671 .728927 -3.672364 -.810977

SF12: Mental

Health
Component
Score,
standardized
Equal variances
assumed

.174 .677 -2.420 859 .016 -1.781113 .736103 -3.225884 -.336341

Equal variances

not assumed
-2.421 858.441 .016 -1.781113 .735800 -3.225290 -.336936

Variable Diploma No Diploma t df p db

CES-D 17.59 20.14 3.34 926 .001 2.55

Physical Health 46.28 44.04 -3.076 859 .002 -2.24

Mental Health 47.48 45.70 -2.420 859 .016 -1.78