Dr. Alastair P. C. Davies

PSYC2750: Introduction to Measurement and Statistics
t-tests
You must complete Question 1 AND Question 2.
One of the questions requires a dependent-samples t-test and the other question requires an
independent-samples t-test. You have to determine which is which.
This assessment contributes 25% to the overall grade for the course.
Deadline:
1pm , Tuesday, October 30.
Plagiarism:
All work you submit must be entirely your own. Any student who is found to have used the work of another  student and any student who is found to have provided work for another student to use as their own will get a  FAIL for the assessment and might possibly get a fail for the whole course.
Instructions for Submitting Your Report:
Please note that if you do not follow the instructions below correctly, you will be asked to resubmit your
assignment and so you may miss the submission deadline.
What to Submit:
When you have completed BOTH Question 1 AND Question 2, you must submit the following in ONE SINGLE email:
• this Word document (saved as ‘t-test.doc’)
• TWO SPSS input files (each saved as ‘.sav’); one for Question 1 (saved as t-test-Q1.sav) and the
other for Question 2 (saved as t-test- Q2.sav).
 
 
How to Submit:
Email your report to me at daviesal@regents.ac.uk from your Regent’s email account. NOTE: So that you have
proof that you sent it, please make sure that your email settings are such that your sent emails are
recorded.
Late Penalty:
Unless a student gains authorization for late submission and provides valid supporting documentation, failure
to submit the assessment before the deadline will mean the student’s grade for the assessment will be capped
at a pass grade of D (60%).
IMPORTANT: You must answer Question 1 AND Question 2.
Question 1.
Note: After you have run the appropriate t-test, you must copy and paste the relevant two tables from the
SPSS output file onto this document (as you have done in class).
A major fast food company would like to improve its image following a lawsuit.
Before embarking on a major marketing campaign for its “new and improved image”, the company wants to test
whether its new image will significantly improve sales at its stores in comparison to its old image.
The company records the total amount of sales in dollars at each store before the campaign is launched and
after the campaign is launched.
Below are the sales figures.
OLD NEW
15000 15000
11000 13000
10000 18000
12000 12000
14000 16000
10000 10000
11000 18000
11000 19000
1. What is the dependent variable? (1 point)
 
2. What is the independent variable and what are its levels? (2 points)
 
3. What is the null hypothesis? (1 point)
 
4. What is the alternative hypothesis? (1 point)
5. Are the samples dependent or independent? You MUST explain your
answer (2 points)
6. Is this a 1-tailed or 2-tailed test? You MUST explain your
answer (2 points)
7. Run the appropriate t-test on the data. (10 points)
Copy and paste here, the relevant TWO tables from the SPSS output file.
 
8. Does the assumption of homogeneity (equality of variances) need to
be tested? You MUST explain your answer (2 points)
9. What is the mean and SD of sales for the new image and the old
image? (2 points)
 
 
10. What is the p-value of the t-test? (1 point)
11. Is the t-test significant? You MUST explain your answer (2 points)
12. Should you reject or fail to reject the null hypothesis? You MUST
explain your answer (2 points)
 
 
13. Write your results in APA format. (3 points)
 
 
14. Would you advise the company to adopt the “new” image? You
MUST explain your answer (2 points)
Question 2.
Note: After you have run the appropriate t-test, you must copy and paste the relevant two tables from the
SPSS output file onto this document (as you have done in class).
The school board of Anywhere, USA is concerned with getting an important message about the dangers of drug
use out to its students.
One school board member suggested that the message be presented in cartoon format, while another felt it
should be presented in a realistic format.
To determine if there is any difference in the effectiveness of the formats, the school board hires an
experimental psychologist to run the two campaigns on a focus group of children. One sample is shown the
cartoon format and another sample is shown the realistic format.
After watching the films, both samples are asked to rate how effective the campaign was in getting across the
anti-drug message.
Below are the effectiveness ratings. The higher the score, then the more effective the campaign.
Cartoon Realistic
1 2
1 7
5 2
2 4
1 5
2 4
2 2
3 6
1. What is the dependent variable? (1 point)
 
2. What is the independent variable and what are its levels? (2 points)
 
3. What is the null hypothesis? (1 point)
4. What is the alternative hypothesis? (1 point)
 
5. Are the samples dependent or independent? You MUST explain
your answer (2 points)
 
6. Is this a 1-tailed or 2-tailed test? You MUST explain your answer
(2 points)
 
7. Run the appropriate t-test on the data. (10 points)
Copy and paste here, the relevant TWO tables from the SPSS output file.
 
8. What is the mean and SD of ratings for the cartoon format and the
realistic format? (2 points)
 
9. Does the assumption of homogeneity (equality of variances) need to
be tested? You MUST explain your answer (2 points)
10. What is the p-value of the Levene’s Test? (1 point)
 
 
11. Is the Levene’s test significant? You MUST explain your answer
(2 points)
 
 
12. Can we assume equality of variances? You MUST explain your answer
(2 points)
13. What is the p-value of the t-test? (1 point)
14. Is the t-test significant? You MUST explain your answer (2 points)
15. Should you reject or fail to reject the null hypothesis? You MUST
explain your answer (2 points)
16. Write your results in APA format. (3 points)
17. Would you advise the school board to use the cartoon or the
realistic format? You MUST explain your answer (2 points)
When you have completed BOTH Question 1 AND Question 2, you must submit the following in ONE SINGLE email:
• this Word document (saved as ‘.doc’)
• TWO SPSS input files (each saved as ‘.sav’); one for Question 1 and the other for Question 2.
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