Homework SourseA test for GERD Gastric Esophageal Reflux Disease intended t
A test for GERD (Gastric Esophageal Reflux Disease) intended to determine if a subject has GERD has been developed. To test its ability to discriminate Normal(C) from GERD patient was measured twice over time. Does the test separate the results by Disease? Are there other consideration?
USE TWO WAY ANOVA TO SOLVE THIS.
Use statistical software to solve and elaborate as much as possible. Thanks
| Group | Test | Result | Subject |
| GERD | 1 | 103 | 1 |
| GERD | 1 | 177 | 2 |
| GERD | 1 | 156 | 3 |
| GERD | 1 | 154 | 4 |
| GERD | 1 | 157 | 5 |
| GERD | 1 | 162 | 6 |
| GERD | 1 | 159 | 7 |
| GERD | 1 | 167 | 8 |
| GERD | 1 | 153 | 9 |
| GERD | 1 | 163 | 10 |
| C | 1 | 172 | 1 |
| C | 1 | 197 | 2 |
| C | 1 | 161 | 3 |
| C | 1 | 150 | 4 |
| C | 1 | 171 | 5 |
| GERD | 2 | 133 | 1 |
| GERD | 2 | 170 | 2 |
| GERD | 2 | 156 | 3 |
| GERD | 2 | 148 | 4 |
| GERD | 2 | 151 | 5 |
| GERD | 2 | 166 | 6 |
| GERD | 2 | 154 | 7 |
| GERD | 2 | 170 | 8 |
| GERD | 2 | 145 | 9 |
| GERD | 2 | 163 | 10 |
| C | 2 | 177 | 1 |
| C | 2 | 182 | 2 |
| C | 2 | 157 | 3 |
| C | 2 | 160 | 4 |
| C | 2 | 159 | 5 |
Solution
SPSS Repeated measure ANOVA is applied for the nested design
Descriptive Statistics
Group
Mean
Std. Deviation
N
Test1
1
155.1000
19.63811
10
2
170.2000
17.42699
5
Total
160.1333
19.72260
15
Test2
1
155.6000
11.93687
10
2
167.0000
11.59741
5
Total
159.4000
12.68745
15
Tests of Within-Subjects Effects
Measure: MEASURE_1
Source
Type III Sum of Squares
df
Mean Square
F
Sig.
test
Sphericity Assumed
12.150
1
12.150
.199
.663
Greenhouse-Geisser
12.150
1.000
12.150
.199
.663
Huynh-Feldt
12.150
1.000
12.150
.199
.663
Lower-bound
12.150
1.000
12.150
.199
.663
test * Group
Sphericity Assumed
22.817
1
22.817
.373
.552
Greenhouse-Geisser
22.817
1.000
22.817
.373
.552
Huynh-Feldt
22.817
1.000
22.817
.373
.552
Lower-bound
22.817
1.000
22.817
.373
.552
Error(test)
Sphericity Assumed
795.650
13
61.204
Greenhouse-Geisser
795.650
13.000
61.204
Huynh-Feldt
795.650
13.000
61.204
Lower-bound
795.650
13.000
61.204
To test the difference between test1 and test2 , calculated F=0.199, P=0.663. The test is not significant.
We conclude that there is no significant difference between test1 and test2.
Tests of Between-Subjects Effects
Measure: MEASURE_1
Transformed Variable: Average
Source
Type III Sum of Squares
df
Mean Square
F
Sig.
Intercept
699624.017
1
699624.017
1592.714
.000
Group
1170.417
1
1170.417
2.664
.127
Error
5710.450
13
439.265
To test the difference between two groups , calculated F=2.664, P=0.127. The test is not significant.
We conclude that there is no significant difference between GERD and C.
SPSS syntax
GLM Test1 Test2 BY Group
/WSFACTOR=test 2 Polynomial
/METHOD=SSTYPE(3)
/PRINT=DESCRIPTIVE
/CRITERIA=ALPHA(.05)
/WSDESIGN=test
/DESIGN=Group.
| Descriptive Statistics | ||||
| Group | Mean | Std. Deviation | N | |
| Test1 | 1 | 155.1000 | 19.63811 | 10 |
| 2 | 170.2000 | 17.42699 | 5 | |
| Total | 160.1333 | 19.72260 | 15 | |
| Test2 | 1 | 155.6000 | 11.93687 | 10 |
| 2 | 167.0000 | 11.59741 | 5 | |
| Total | 159.4000 | 12.68745 | 15 |
