Midterm Exam
The purpose of this examination is to practice using SPSS to analyze the data. You should attempt each of the questions detailed on the following pages. You will need to have read through the provided materials in the class first to familiarize yourself with its contents and revise the various statistical procedures covered.
There are a number of parts to this exercise.
- In Part A, you are asked to create your own data file and to perform analyses on this data file.
- In Part B, you will be asked to interpret some output generated by SPSS.
- In Part C, you will be using the data file attached in mid-term dropbox. Full details of this data file is also included in the dropbox, and you should read through this section thoroughly before beginning. This is a real data file that is condensed from data collected by Postgraduate Diploma of Psychology students.
- In Part D, you will estimate sample size by using G*power.
The following rules apply for this assignment:
- If applicable, answer the question under three headings.
- SPSS syntax
- Necessary SPSS output
- Interpretation and/or conclusion of your analysis
- Organize your work in a reasonably neat and coherent way. Work scattered all over the page without a clear ordering will receive very little credit.
- Only necessary output from the SPSS software should be in the submitted exam.
- You are required to work INDIVIDUALLY.
- Justification does not include hundreds of pages of computer output with hopes you covered all aspects. Justification is a well thought out and well-articulated rationale for what you do!
Do not JUST SUBMIT SPSS OUTPUTS or CODES
Part A
| Sample questionnaire
1. Sex ___ Male ___ Female
2. Age in years __________
3. Education level (please indicate the highest level of schooling that you completed)
_____ Year 10 _____ Year 12 ______ University or College
4. Are you currently on a diet to lose weight? ____ Yes ____ No
Mastery Scale
Please indicate how much you either agree or disagree with each of the following statements.
Write a number from 1 to 4 on the line next to each statement.
strongly disagree 1 2 3 4 strongly agree
1. ______ I have little control over the things that happen to me
2. ______ I can do just about anything I really set my mind to
3. ______ There is really no way I can solve some of the problems I have
4. ______ There is little I can do to change many of the important things in my life
5. ______ What happens to me in the future mostly depends on me
6. ______ I often feel helpless in dealing with the problems of life
7. ______ Sometimes I feel that I’m being pushed around in life |
- 1. Prepare a codebook for this questionnaire, detailing each of the variable names and codes to be used to prepare the data for entry into SPSS. (3 points)
Using the codebook you developed, describe how you would create value labels for Question 3 (Education level). Describe the steps you would use in SPSS. (3 points)
- Using SPSS, create a new data file for this questionnaire. Enter some pretend data in this data file (for at least five cases). (3 points)
4. It is important to check your data set for errors before conducting your major analyses.
(a) Describe how you would go about doing this using SPSS. In particular, how would you identify cases that had values that did not fall in the range of possible values for a particular variable? (3 points)
(b) Perform a check for errors on your pretend data file. Correct any errors you find.
(3 points)
- Using your pretend data file, calculate total scale scores for the Mastery scale used in the questionnaire (make sure you reverse the negatively worded items first). High scores on the Mastery scale should represent high levels of mastery. Report the mean and standard deviation for the Mastery scale. (3 points)
- Create a new variable by recoding the responses to Question 3 (education level) so that there are only two groups (Yr 10 and Yr 12 = 0; University/College = 1). (3 points)
- Create a new age group variable (agegp4) that breaks the sample into 4 groups:
18-25yrs = 1, 26-45yrs =2, 46-60yrs = 3, 61yrs and above = 4. Remember to attach value labels to describe what each value in the new variable represents. (6 points)
Part B
- A market researcher is interested in the coffee drinking habits of males and females. He asks a sample of male and female office workers to record the number of cups of coffee they consume during a week.
(a) Which statistical technique could the researcher use to determine if males and females differ in terms of the number of cups of coffee consumed in a week? Explain why you have chosen this technique. (6 points)
(b) What assumptions should you check for when using the technique that you chose in question 2(a) above. (3 points)
- The following output was obtained using SPSS.
| Coefficientsa |
| Model |
Unstandardized Coefficients |
Standardized Coefficients |
t |
Sig. |
| B |
Std. Error |
Beta |
| 1 |
(Constant) |
-11.823 |
8.806 |
|
-1.343 |
.198 |
| hours spent revising |
.551 |
.171 |
.456 |
3.226 |
.005 |
| anxiety |
.104 |
.058 |
.179 |
1.796 |
.091 |
| A-level entry points |
1.989 |
.469 |
.581 |
4.239 |
.001 |
| a. Dependent Variable: exam score |
(a) Which parametric statistical technique was used to obtain this output?(3 points)
(b) What research question/s could be addressed using this output? (3 points)
(c) Interpret this output in terms of the research question/s you gave in question 3(b), above. (3 points)
- A researcher is interested in assessing the impact of a number of changes in a public health department on the job satisfaction of employees. Before the changes are implemented the researcher distributes a questionnaire to a sample of employees, which measures their attitudes to their work and their overall job satisfaction. The same questionnaire is distributed to the same group of employees one month after the workplace changes were implemented and again three months later.
(a) Which parametric statistical technique could the researcher use to see if workers’ job satisfaction levels had changed across the three time periods measured? Briefly justify your answer. (3 points)
(b) What non-parametric technique (if any) could be used to explore this question? (3 points)
Part C
In this part, you will need to open the data file that accompanies in dropbox folder, survey.sav. Details of the questionnaire, the scales used, and the codebook are provided in dropbox.
- Using the survey.sav data file, report the descriptive statistics for gender, age, marital status, and education level. Write up the results of these descriptive statistics as they would appear in the Method section of a research article. (6 points)
- (Bonus Question) It is essential to check the reliability of scales used in your study. Check the Cronbach alpha values for the following scales: (4 points)
(a) Mastery scale
(b) Life Satisfaction scale
(c) Perceived Control of Internal States scale
(d) Perceived Stress scale
- A researcher is interested in exploring the possibility of gender differences in levels of perceived stress (total score) controlling for age (in years as continuous).
(a) Perform the appropriate statistical analysis to address this question. Be sure to check that you have not violated any assumptions. (3 points)
(b) Report the conclusions (6 points)
- The same researcher is interested in exploring the relationship between perceived control (tpcoiss) and life satisfaction. She suspects that higher levels of perceived control would be associated with greater life satisfaction.
(a) Perform whatever analyses you feel are appropriate to address this question (including assumption testing if applicable). (3 points)
(b) Describe the analyses you performed and report on these analyses and the results, as you would in a research report. (3 points)
- A researcher is interested in exploring the effect of sex and age group (age as categorical variable) on Life Satisfaction scores.
(a) Using the sex and agegp3 variables, perform the appropriate analyses to address this question. For this particular question, it is not necessary to show assumption testing. (3 points)
(b) Report the conclusions (6 points)
Part D
Using G power, estimate the sample size for following scenario.
A community health worker wants to compare two intervention, A and B, for reduction of stress due to COVID pandemic. He hypothesizes that intervention A (Group 1) will be better than intervention B (Group 2), in terms of overall stress reduction. He plans to get a match paired sample of participants from his community and randomly assign them to one of the two interventions. He decides to do matching based on demographic variables. At the end of the experiment, which lasts 2 weeks, a total PSS (total perceived stress score) will be estimated on each participant. He also expects that the average difference in total perceived stress score between the two groups will be about 5 points. Furthermore, she also assumes the standard deviation of total stress score for intervention A to be 5 and the standard deviation for intervention B to be 8. The community health worker wants to know the number of subjects needed in each group and total sample size assuming equal sized groups with 95% power. (Hint: Use G power to estimate the total sample size. Also assume the correlation between groups to be 0.5). You may attached screenshot from G*Power to receive a partial credit for this question (6 points)