## INDEPENDENT-SAMPLES T-TESTS

SPSS Homework 2 Instructions:

Independent-Samples t-Tests

Part 1:

Green & Salkind: Lesson 24 – Exercises 1–5

The following helpful tips are numbered to correspond with the exercise number to which they refer:

1.     Type the t and p values out underneath your copied and pasted output. (3 pts)

2.     Instead of identifying these values on your output, as the text states, write them into your Word file as written answers for #2 a, b, and c. Letter c is basically asking, “What are the results of Levene’s test in the output (F and p values)?” (3 pts, 1 point for each letter)

3.     The effect size statistic must be computed by hand (or calculator!). Use the second “easier” formula for d (containing t, N1, and N2 values) found in the section on “Effect Size Statistics” in the Green & Salkind text in Lesson 24. Do not use the formula with “SD pooled” or compute SD pooled—these are not covered in depth and are not necessary. (3 pts)

4.     Write a current APA-style Results section based on your analyses. All homework Results sections must follow the example given in the SPSS tutorials and the Course Content document “Writing Results of Statistical Tests in Current APA Format” (note: you do not have to refer to a figure). Remember to include a decision about the null hypothesis. (3 pts)

5.     Create a boxplot (not an error bar graph) using the following steps (covered also in Lesson 21) (3 pts)

a.      Go to Graphs>Legacy Dialogs>Boxplot>Select “Simple”>Select “Summaries for Groups of Cases”

b.     Click “Define”: Variable = “Time Spent” (this is your dependent variable) and Category Axis = “Weight” (this is your independent, or grouping, variable)

c.      OK

Part 2:

1.     A learning psychologist is interested in studying the ability of subjects to recall a list of food words after participating in 1 of 2 priming tasks. He assigns students to 2 groups: each student in Group 1 is instructed to think about a favorite meal for 2 minutes; each student in Group 2 is instructed to think about a favorite mode of transportation for 2 minutes. They are then given a list of 15 food words and are given 1 minute to memorize them. After 1 minute, the lists are collected and students are instructed to write down as many words as they can recall. Using the table below, enter the data into a new SPSS data file and use an independent-samples t-test to analyze the claim that the 2 priming methods result in a different number of words recalled.

The steps will be the same as the ones you have been practicing in Part 1 of the assignment— the only difference is that you are now responsible for creating the data file as well. Remember to name and define your variables under the “Variable View,” then return to the “Data View” to enter the data. (3 pts for output)

13

11

9

12

8

9

14

7

12

10

12

5

3

9

10

13

7

7

6

10

2.     Create a boxplot illustrating the differences between the 2 priming methods. (3 pts)

3.     Write a current APA-style Results section based on your analyses. All homework Results sections must follow the example given in the SPSS tutorials and the Course Content document “Writing Results of Statistical Tests in Current APA Format” (note: you do not have to refer to a figure). Remember to include a decision about the null hypothesis. (4 pts)

Part 3: Cumulative Homework

1.     The effects of a new faith-based anxiety treatment program are studied in a group of elderly patients with Generalized Anxiety Disorder (GAD). One of the outcome measures is the Geriatric Anxiety Inventory (GAI) (Pachana et al., 2007), a measure with possible scores of 0–20, with higher scores indicating higher anxiety. A large group of elderly patients completed the GAI before treatment. Fifteen patients with GAI scores of 10 or higher were chosen to participate in the study. The patients underwent the treatment program and completed the GAI at the end of treatment. The scores are listed below. Do the elderly patients exhibit lessened anxiety, as demonstrated by their GAI scores, after participating in the faith-based treatment program? Choose the correct test to analyze this question, set up the SPSS file, and run the analysis. Follow the directions under the table below.

GAI Score Before Treatment

GAI Score After Treatment

12

13

19

14

10

14

16

12

11

17

18

12

11

15

16

7

11

12

13

9

10

12

10

11

13

16

8

12

9

14

a)     Paste the appropriate SPSS output. (5 pts)

b)     Paste the appropriate SPSS graph. (5 pts)

c)     Write a current APA-style Results section based on your analyses. All homework Results sections must follow the example given in the SPSS tutorials and the Course Content document “Writing Results of Statistical Tests in Current APA Format” (note: you do not have to refer to a figure). Remember to include a decision about the null hypothesis. (5 pts)

Submit this assignment by 11:59 p.m. (ET) on Monday of Module/Week 2.