Homework SourseRecently UC Santa Barbara received a large grant from Acme I
Recently UC Santa Barbara received a large grant from Acme Inc. As part of the grant 20 personal computers were given to the university as well as a series of instructional software programs designed to improve writing skills of college students. An educational researcher decided to evaluate the usefulness of these programs and designed the following experiment for that purpose. After announcing the project to several large classes on campus, 30 students volunteered to participate in the study. Ten students were randomly assigned to one of the three groups. Group 1 was instructed on how to use the PC and the writing programs. Group 2 learned how to use the word processing program but received no instruction on improving their writing skills. The 3rd group received no special instruction and served as a control group. Before beginning the treatment all students were asked to write a 2000 word essay with the instruction to
Solution
SPSS is used for analysis
ANCOVA is used to compare post test scores controlling pre test scores.
Descriptive Statistics
Dependent Variable: posttest
Group
Mean
Std. Deviation
N
1
10.60
4.169
10
2
13.70
2.669
10
3
14.70
2.541
10
Total
13.00
3.572
30
Tests of Between-Subjects Effects
Dependent Variable: posttest
Source
Type III Sum of Squares
df
Mean Square
F
Sig.
Corrected Model
236.188a
3
78.729
15.297
.000
Intercept
51.220
1
51.220
9.952
.004
pretest
144.788
1
144.788
28.133
.000
Group
67.336
2
33.668
6.542
.005
Error
133.812
26
5.147
Total
5440.000
30
Corrected Total
370.000
29
a. R Squared = .638 (Adjusted R Squared = .597)
Is there any statistical evidence to indicate that the populations differ in their final writing samples? State the appropriate omnibus test statistics, degrees of freedom, and p value.
Calculated F(2,26) =6.542, P=0.005. The calculated P <0.05.
The null hypothesis is rejected.
There are statistical evidence to indicate that the populations differ in their final writing samples.
If there are differences, which group or groups wrote the best essay? Provide the appropriate
| Descriptive Statistics | |||
| Dependent Variable: posttest | |||
| Group | Mean | Std. Deviation | N |
| 1 | 10.60 | 4.169 | 10 |
| 2 | 13.70 | 2.669 | 10 |
| 3 | 14.70 | 2.541 | 10 |
| Total | 13.00 | 3.572 | 30 |
