Analysis of Variance SPSS instructions:
Open SPSS
Analyze the data for #1. Remember that SPSS assumes that all the scores in a row are from the same participant. In this study, there are 15 participants divided into three groups of five. Therefore, each of the 15 participants will be described by two variables, type of therapy and the number of activities of daily living performed.
If "1" represents the group receiving individual therapy for 1 hour every 2 weeks, "2" represents the group receiving 1 hour of individual therapy each week, and "3" indicates the group receiving 2 hours of individual therapy each week, the first participant will be described by entering "1" in the top cell of the first column in the Data View window and "16" in the top cell of the second column to indicate that the participant underwent 1 hour of therapy every 2 weeks and performed 16 activities of daily living. The second participant will be described by "1" and "15", and the third by "1" and "18".
When the two variables have been entered for the five participants in this group, repeat the process for participants who underwent 1 hour of individual therapy each week, using "2" to describe their therapy group. When the two variables for the five participants in this group have been entered, repeat the process for Group 3, entering "3" in the first column. In the Variable View window, change the first variable name to "THERAPY" and the second to "ADL" and set the decimals for both to zero.
Click Analyze à Compare Means à One-Way ANOVA àSince "THERAPY" is already selected, you can click the arrow to move the variable to the Factor window. Select "ADL" and click the arrow to move the variable to the Dependent List window, which instruct SPSS to conduct the analysis of variance on the number of activities performed.
1. Keep in mind that the clients in Group 1 will receive 1 hour of therapy every 2 weeks, the clients in Group 2 will receive 1 hour of therapy every week, and the clients in Group 3 will receive 2 hours of therapy every week.
Use the five steps of hypothesis testing to determine whether the observed differences in the number of activities in the following table performed by the three groups are statistically significant at the .05 level of significance. Clearly indicate each of the five steps.
Calculate the effect size for the study. Explain your results.
|
CLIENT
|
GROUP 1
|
GROUP 2
|
GROUP 3
|
|
1
|
15
|
19
|
24
|
|
2
|
18
|
19
|
21
|
|
3
|
16
|
17
|
22
|
|
4
|
21
|
23
|
20
|
|
5
|
19
|
20
|
22
|
2. A researcher interested in the relationship between student perception of the probability of success in a statistics course and student motivation has administered an inventory designed to assess motivation in 18 students.
The students have been divided into groups as follows: Students in Group 1 believe they are highly likely to succeed in the course, students in Group 2 believe they have an intermediate probability of success, and students in Group 3 believe they have little chance of success.
Use the five steps of hypothesis testing to determine whether the observed differences in level of motivation in the following table are statistically significant at the .05 level of significance. Clearly indicate each of the five steps.
Calculate the effect size for the study. Explain the results of the hypothesis-testing procedure to someone who is familiar with the t test for independent means, but not with analysis of variance.
|
SUBJECT
|
GROUP 1 (HIGH)
|
GROUP 2 (INTERMEDIATE)
|
GROUP 3 (LOW)
|
|
1
|
9.0
|
3.5
|
8.0
|
|
2
|
8.5
|
5.5
|
5.5
|
|
3
|
6.5
|
3.5
|
6.5
|
|
4
|
7.0
|
3.5
|
4.5
|
|
5
|
8.0
|
6.5
|
5.5
|
|
6
|
5.5
|
7.0
|
6.0
|
3. Due to the increasing number of trails involving testimony by behavioral scientists, a professional organization of behavior scientists asked judges, attorneys, jurors, and law enforcement officials to use a 10-point scale to rate the effect of such testimony on trial outcomes.
The results are presented in the table below. Use the five steps of hypothesis testing to determine whether the observed differences in effectiveness ratings are statistically significant at the .01 level of significance. Clearly indicate each of the five steps.
Calculate the effect size for the study. Explain your results.
|
CATEGORY
|
N
|
M
|
S2
|
|
Judges
|
6
|
7.00
|
1.99
|
|
Attorneys
|
6
|
5.83
|
1.37
|
|
Jurors
|
6
|
7.83
|
1.37
|
|
Law Enforcement
|
6
|
3.00
|
3.61
|