Question

Part 2 – SPSS APPLICATION from this week’s assigned readings and presentations (28 pts)

Problem Set 1: The independent-samples t test (7 pts) Research Scenario: A clinical psychologist is studying whether there is a difference between veterans diagnosed with PTSD and veterans without PTSD in reduction of anxiety after aerobic exercise. All veterans in this study agree to complete 30 minutes of aerobic exercise 5 days a week for 4 weeks and began with similar levels of reported anxiety. Scores shown are calculated difference scores in anxiety, with higher scores indicating more of a reduction in anxiety (scale measurement). Using this table, enter the data into a new SPSS data file and run an independent samples t test to test whether aerobic exercise differentially affects anxiety in veterans with and without PTSD. Remember to name and define your variables under the “Variable View,” then return to the “Data View” to enter and analyze the data. Remember, data will be entered differently than in a paired samples t-test. Specifically, you will have one variable (“Group”), with 0 = no PTSD and 1 = PTSD. The other variable is “Change”. Thus, data will not be entered exactly as shown below.

NoPTSD	PTSD
24	25
23	23
22	27
30	19
31	22
30	13
38	18
25	28
33	21
38	31

1. Paste relevant SPSS output. (2 pts)

2.     Create an appropriate graph to display this data. (2 pts)

3. Write an APA-style Results section based on your analysis. All homework “Results sections” should follow the examples provided in the presentations and textbooks. They should include the statistical statement within a complete sentence that mentions the type of test conducted, whether the test was significant, and if relevant, the effect size. Don’t forget to include a decision about the null hypothesis. (3 pts)

Problem Set 2: Pearson’s correlation (7 pts) Research Scenario: Is there a positive relationship between grit and dieting success? A researcher examined this issue by having people complete a grit inventory using a Likert-based scale (range 1 – 7), where higher numbers indicate more “grit”. Dieting success was measured using a likert-based inventory as well, with higher numbers indicating more success (range 1-7). Enter the data shown here into SPSS to run an analysis to test whether increased grit is associated with higher dieting success. Grit Success 3.5 2.3 2.0 1.1 1.7 0.3 1.8 0.1 2.7 0 3.5 0.7 3.9 3.7 4.1 5.5 3.5 3.7 4.7 6.7 5.1 5.9 3.2 5.3 5.6 4.4 4.1 2.8

4.     Paste relevant SPSS output. (2 pts)

5.     Create an appropriate graph to display this data. (2 pts)

6.     Write an APA-style Results section based on your analysis. All homework “Results sections” should follow the examples provided in the presentations and textbooks. They should include the statistical statement within a complete sentence that mentions the type of test conducted, whether the test was significant, and if relevant, coefficient of determination and its interpretation. Don’t forget to include a decision about the null hypothesis. (3 pts)

Note: Please solve it by text not in hand written form.

Answer 1

Problem Set 1: The independent-samples t test (7 pts)

From the above boxplot of the score with respect to two levels of PTSD, the median of the score for PTSD is less than the first quarter of the scores of the No PTSD. Hence, the two groups may have significance mean score.

Group Statistics
	PTSD	N	Mean	Std. Deviation	Std. Error Mean
Score	No PTSD	10	29.4000	5.85377	1.85113
	PTSD	10	22.7000	5.31350	1.68028
Independent Samples Test
		Levene's Test for Equality of Variances		t-test for Equality of Means
									95% Confidence Interval of the Difference
		F	Sig.	t	df	Sig. (2-tailed)	Mean Difference	Std. Error Difference	Lower	Upper
Score	Equal variances assumed	.202	.659	2.680	18	.015	6.70000	2.50000	1.44769	11.95231
	Equal variances not assumed			2.680	17.834	.015	6.70000	2.50000	1.44418	11.95582

Conclusion: The p-value for the two-tail test is 0.015 and less than the 0.05 level of significance. Hence, we can conclude that there is a difference between veterans diagnosed with PTSD and veterans without PTSD in the reduction of anxiety after aerobic exercise at the 0.05 significance level.