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)

Answer 1

SPSS OUTPUT:

Group Statistics
	GRP	N	Mean	Std. Deviation	Std. Error Mean
ANXIETY	No PTSD	10	29.40	5.854	1.851
	PTSD	10	22.70	5.314	1.680

Independent Samples Test
		Levene's Test for Equality of Variances		t-test for Equality of Means
		F	Sig.	t	df	P VALUE	Mean Difference	Std. Error Difference	95% Confidence Interval of the Difference
									Lower	Upper
ANXIETY	Equal variances assumed	.202	.659	2.680	18	0.015	6.700	2.500	1.448	11.952
	Equal variances not assumed			2.680	17.834	0.015	6.700	2.500	1.444	11.956