SPSS

PSYC 515 SPSS M1 1

REVIEW SPSS WORKSHEET INSTRUCTIONS

Scenario 1 A major university would like to improve its tarnished image following a large on-campus scandal. Its marketing department develops a short television commercial and tests it on a sample of n = 10, the first ten students who entered a housing commons area who agreed to participate. Attitudes about the university are measured with a short questionnaire, both before and after viewing the commercial. Attitudes were on a scale of 0 – 20, which higher numbers reflecting better attitudes. Use the provided data to examine whether the commercial improved the university’s image. The data are as follows:

Person X1 (before) X2 (after) A 15 15 B 11 13 C 10 18 D 11 12 E 14 16 F 10 10 G 11 19 H 10 20 I 12 13 J 15 18

1. In this specific scenario, what is the independent variable? Is it between or within subjects? How many levels does it have, and what are they?

ANSWER The IV is the commercial that is being shown and it is considered a within subjects because the same individuals were tested before and after watching the commercial to determine the attitude scale.Two level because it is measuring attitude before and after viewing the TV commercial.

2. In this specific scenario, what is the dependent variable? What is its scale of measurement (nominal, ordinal, or scale)?

ANSWER The DV is the attitude scale being measured from 0-20 before and after the commercial. The scale of measurement is scale.

3. Paste all relevant statistical output in the space provided below: ANSWER

Paired Samples Statistics

Mean N Std. Deviation Std. Error Mean

Pair 1 BEFORE 11.90 10 2.025 .640

AFTER 15.40 10 3.340 1.056

Paired Samples Correlations

N Correlation Significance

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PSYC 515 SPSS M1 2

One-Sided p Two-Sided p

Pair 1 BEFORE & AFTER 10 .105 .386 .773

Paired Samples Effect Sizes

Standardizera Point Estimate

95% Confidence Interval

Lower Upper

Pair 1 BEFORE - AFTER Cohen's d 3.719 -.941 -1.677 -.170

Hedges' correction 3.884 -.901 -1.606 -.163

a. The denominator used in estimating the effect sizes.

Cohen's d uses the sample standard deviation of the mean difference.

Hedges' correction uses the sample standard deviation of the mean difference, plus a correction factor.

4. Create an appropriate graph in SPSS and paste it in the space provided below: ANSWER

5. Present the results using APA format. This includes a full write-up to include a complete statistical notation as shown in the weekly presentations. The write-up also needs interpretation. If significant, state how. If it is not significant, what does that mean in layman’s terms? Additional examples of APA

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PSYC 515 SPSS M1 3

results sections are also available in the “Helpful Hints” document. ANSWER To test the hypothesis that the attitude before the TV commercial (M= 11.90, SD= 2.025) and the attitude after the TV commercial (M= 15.40, SD= 3.340) improved after viewing the TV commercial, a dependent samples t-test was performed. The test found a statistically significant difference between the attitude scores before and after the participants viewed the TV commercial that is described t (9)= -2.976, p < .05. Therefore, we reject the null hypothesis that the attitudes improved about the school’s image, after viewing the TV commercial.

6. Do you think this experiment has more internal validity or external validity? Explain your answer. (You may want to review chapters 9-10 in your Jackson e-book).

ANSWER Technically, this could have been an internal or external validity. This specific test would be considered an external validity because the participants that were used were generalized as they only used the first 10 individuals that walked into the housing commons area. So we therefore would assume that those students were ones that specifically lived there, hince going into the housing area, but there was no details if they were specifically attending the college and all in the same grade, for example. So, without that specific information, we can assume that those 10 people are random and could be a possible manipulation to the study for they had no specific interest in the commercial in the first place. For example, if those 10 participants were indeed people that all attended the college, they most likely would have a better outlook since they are the one attending in the first place. If those individuals happened to be parents, then they could have an even more positive outlook because they are sending their kids there. Because the example does not specify a specific category of the participants, there is a factor of the unknown that would make the test manipulated by population. Final answer, it would be considered an Internal Validity.

Scenario 2

To measure whether test performance can be predicted based on one’s anxiety, a researcher asked his students to come to the lab 15 minutes before they were to take an exam in his class. The researcher measured the students' heart rates and then matched these scores with their exam performance after they had taken the exam. Use the data below and SPSS to test whether heart rate can predict test performance in the population.

Student Heart Rate Exam Score

A 76 78

B 81 68

C 60 88

D 65 80

E 80 90 Page 3 of 9

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PSYC 515 SPSS M1 4

F 66 68

G 82 60

H 71 95

I 66 84

J 75 75

K 80 62

L 76 51

M 77 63

N 79 71

7. In this specific scenario, are the two variables of interest? Which is the IV and which is the DV? What is the scale of measurement for each variable?

ANSWER The two variables are heart rate and the exam scores. The scale for each would be considered interval and ratio or a scale measurement on SPSS. The IV is the heart rate and the DV is the exam score which is what you are predicting, your data.

8. Relate to this specific scenario: What is the null hypothesis? What is the alternate / research hypothesis? Which one do you statistically assess?

ANSWER The null hypothesis: There is no difference/relationship between a person’s heart rate an exam score. The alternate: There is a relationship between a person’s heart rate and predicted test score. The null hypothesis is the one where you conduct an inferential statistical test.

9. Paste all relevant statistical output in the space provided below: ANSWER

Correlations Page 4 of 9

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PSYC 515 SPSS M1 5

Heart_Rate Exam_Score

Heart_Rate Pearson Correlation 1 -.481

Sig. (2-tailed) .082

N 14 14

Exam_Score Pearson Correlation -.481 1

Sig. (2-tailed) .082

N 14 14

10. Create an appropriate graph in SPSS and paste it in the space provided below: ANSWER

11. Present the results using APA format. This includes a full write-up to include a complete statistical notation as shown in the weekly presentations. The write-up also needs interpretation. If significant, state how. If it is not significant, what does that mean in layman’s terms? Additional examples of APA results sections are also available in the “Helpful Hints” document.

ANSWER A Pearson’s r correlation was used to examine whether there is a relationship between the heart rate and exam scores. No relationship was found r (12) = -.481, p = .082 (two tailed). The null hypothesis is retained; there is no relationship.

12. What is a potential confound of this study? Provide a sufficient justification.

ANSWER The researcher asked the students to come in 15 minutes early to have their heart rate taken. This

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PSYC 515 SPSS M1 6

could possibly leave the students more anxious and in turn would give false readings based on their anticipated anxiety to the research and not the study itself. If the researcher wanted to know less manipulated beginning heart rates, he could have the students wear a heart monitor for 24 hours and then have the heart rate recordings over a duration of time, including the time of a test.

Scenario 3

A psychology instructor at a large university teaches statistics. There are 22 students in the class, and he has broken them into two groups. Each group has a different graduate assistant who is responsible for running separate breakout lecture and lab sections of the course. One graduate assistant (GA) has lots of experience teaching, while the other has more limited experience. The instructor wants to check for comparable learning across the two GAs, hoping students receive similar experiences (i.e., to find no difference). The data below are the scores (out of 100) of the students on the first midterm. Use it to test whether there is a difference between the groups.

Group 1 (less experienced GA)

Group 2 (more experienced GA)

60 70

65 85

69 72

58 83

57 81

59 69

52 65

72 75

70 79

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PSYC 515 SPSS M1 7

65 71

75 80

13. In this specific scenario, what is the independent variable? Is it between or within subjects? How many levels does it have, and what are they?

ANSWER IV is Group on that is less experienced and Group 2 that is more experienced.. the graduate assistant. This is a between subjects and there is two levels since there are two groups, nominal on SPSS.

14. In this specific scenario, what is the dependent variable? What is its scale of measurement? ANSWER The DV is the midterm scores and its scale of measurement is scale.

15. Paste all relevant statistical output in the space provided below: ANSWER

Paired Samples Statistics

Mean N Std. Deviation Std. Error Mean

Pair 1 Less 63.82 11 7.195 2.169

More 75.45 11 6.517 1.965

Paired Samples Correlations

N Correlation

Significance

One-Sided p Two-Sided p

Pair 1 Less & More 11 .322 .167 .334

Paired Samples Effect Sizes

Standardizera Point Estimate

95% Confidence Interval

Lower Upper

Pair 1 Less - More Cohen's d 8.003 -1.454 -2.300 -.575

Hedges' correction 8.320 -1.399 -2.212 -.553

a. The denominator used in estimating the effect sizes.

Cohen's d uses the sample standard deviation of the mean difference.

Hedges' correction uses the sample standard deviation of the mean difference, plus a correction factor.

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PSYC 515 SPSS M1 8

16. Create an appropriate graph in SPSS and paste it in the space provided below: ANSWER

17. Present the results using APA format. This includes a full write-up to include a complete statistical notation as shown in the weekly presentations. The write-up also needs interpretation. If significant, state how. If it is not significant, what does that mean in layman’s terms? Additional examples of APA results sections are also available in the “Helpful Hints” document.

ANSWERA correlated groups t test was conducted to compare a learning assessment on student between one graduate assistant who has more experience than one graduate assistant who has less experience. This study showed there wasn’t a statistically significant difference t (10) = -4.822, p<.001, r²= .72, 95% CI [-6.26, -17.013]. Therefore we fail to reject the null hypothesis. We cannot say that there is s statistically significant difference in the groups exams from a graduate assistant who has more experience compared to the graduate assistant who has less experience.

18. Using information from this scenario, determine the degrees of freedom and whether this is a one- or two-tailed test. Use the Appendix in your e-book to find the critical value. Do not round – provide the exact critical value below. Label it “critical value”. Also provide the “obtained value” from your SPSS (and label it as such). Compare the critical and obtained values – does the critical value exceed the obtained value? What does this mean in regards to the null hypothesis (would you reject or fail to reject the null hypothesis)?

ANSWER The DF is 22 participants – 2 = 20. This test is a two tailed test because we are looking for a difference in the relationship to occur. Critical Value is 3.850. If you went off the paired samples t test df, that would equal 4.587, with a df = 10. Obtained Value is -4.822. This would mean that you fail to reject the null hypothesis.

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PSYC 515 SPSS M1 9

DONE! Submit this assignment by 11:59 p.m. (ET) on Sunday of Module 1.

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