Please complete the following problems using SPSS (and Excel for graphs). Interpret all results at the .05 significance level and
round to two decimal places.
Record your responses in the spaces provided and make sure you do not miss any questions. Make sure to include statistical notation when appropriate.
1. A researcher wants to evaluate the learning ability of college students with various background sounds during learning. She
randomly
divides
21 participants into three groups. All students study a passage of text for 30 minutes. Those in group 1 study with background sound at a constant volume in the background. Those in group 2 study with background sound that changes volume randomly. Those in group 3 study with no sound at all. After studying, all students take a 10-point multiple choice test about the material. Their scores follow:
(30 points)
Constant sound
|
Random sound
|
No sound
|
7
|
5
|
5
|
4
|
5
|
6
|
6
|
3
|
7
|
8
|
4
|
9
|
6
|
4
|
8
|
6
|
6
|
7
|
9
|
2
|
6
|
A. What statistical test was performed? Be as specific as possible.
(5 points)
B. What is the overall result of the statistical analysis (hint: think “first sentence”)? Include statistical notation.
(5 points)
C. Is the constant sound group significantly different from the random sound group? Describe the relationship and include statistical notation.
(5 points)
D. Is the constant sound group significantly different from the no sound group? Describe the relationship and include statistical notation.
(5 points)
E. Is the random sound group significantly different from the no sound group? Describe the relationship and include statistical notation.
(5 points)
F. Write a sentence in “plain English” that describes the results of the experiment.
(5 points)
2. A researcher wants to evaluate a new 12-week behavioral therapy for children diagnosed with oppositional defiant disorder. The researcher implements the therapy with 7 children, and measures the number of outbursts in a week by each child before starting the therapy (baseline), three months after starting therapy, and six months after starting therapy. Is the therapy effective at reducing outbursts in children diagnosed with oppositional defiant disorder?
(30 points)
Child Name
|
Baseline
|
Month 3
|
Month 6
|
Justin
|
20
|
10
|
6
|
Sarah
|
25
|
6
|
4
|
Anthony
|
17
|
3
|
3
|
Melanie
|
19
|
7
|
4
|
Patrick
|
12
|
3
|
3
|
Isabelle
|
18
|
2
|
1
|
Victor
|
23
|
3
|
4
|
A. What statistical test was performed in order to determine whether the treatment is effective at reducing outbursts? Be as specific as possible.
(5 points)
B. What is the overall result of the statistical analysis (hint: think “first sentence”)? Include statistical notation.
(5 points)
C. Is baseline significantly different from month 3? Describe the relationship and include statistical notation.
(5 points)
D. Is baseline significantly different from month 6? Describe the relationship and include statistical notation.
(5 points)
E. Is month 3 significantly different from month 6? Describe the relationship and include statistical notation.
(5 points)
F. Write a sentence in “plain English” describing the results of the experiment.
(5 points)
Bonus: Graph your results of either question 1 or question 2 – you will not receive more credit if you graph both (include axis titles, chart title, and SEM error bars).
(3 bonus points)
3. In order to better prepare for her 8:00am classes, a statistics graduate student designs an experiment to see how various strategies improve test scores. Getting extra sleep and drinking coffee are often said to be good ways to improve focus in class. She assigns half of her participants to 4 hours of sleep the night before a test and the other half to 8 hours. Within these groups, half of the participants are given 50mg of caffeine the morning of the test and the other half are given 100mg of caffeine. She then measures exam performance on a test with scores ranging from 1-15.
(40 points)
|
4 hours of sleep
|
8 hours of sleep
|
50mg of caffeine
|
10
7
9
7
10
8
9
|
14
12
15
11
12
10
12
|
100mg of caffeine
|
13
10
11
9
15
11
10
|
11
13
9
14
12
10
13
|
A. What test was performed? Be as specific as possible.
(6 points)
B. Write a sentence describing the main effect of sleep (include statistical notation). If the main effect was significant, write a second sentence describing which group scored higher/lower (include statistical notation).
(12 points)
C. Write a sentence describing the main effect of caffeine (include statistical notation). If the main effect was significant, write a second sentence describing which group scored higher/lower (include statistical notation).
(12 points)
D. Write a sentence describing if there was a significant interaction effect or not (include statistical notation). Note: you do not need to describe the different groups here.
(10 points)
Bonus: What do these results suggest? Is there an ideal sleep/caffeine combination that appears to be the most effective or particularly ineffective?
(3 bonus points)
Bonus: Graph these results (include axis titles and chart title)
(3 bonus points)