In a comparison of visual acuity of deaf and hearing children, eye movement rate
ID: 3170604 • Letter: I
Question
In a comparison of visual acuity of deaf and hearing children, eye movement rates are taken on 8 deaf and 8 hearing children. A clinical psychologist believes that deaf children have greater visual acuity than hearing children. Test the psychologist's claim by using the data in the table. (The larger a child's eye movement rate, the more visual acuity the child possesses.) Let alpha = 0.05. Ho: The visual acuity of the two groups is identical. Ha: The visual acuity of the deaf children is greater than the visual acuity of the hearing children. a. Rank the combined data and calculate the Wilcoxon test statistic T. This is a rank sum test. b. Specify the critical region. c. Make a decision about Ho.Explanation / Answer
Deaf
Hearing
Rank
Deaf
Hearing
1.15
1
1.33
2
1.43
3
1.64
4
1.65
5
1.73
6
1.75
7
1.95
8
2.03
9
2.17
10
2.3
11
2.45
12.5
2.45
12.5
2.64
14
3.14
15
3.23
16
Sum
99
37
Since we want to test if the visual acuity of deaf children is greater than the visual acuity of hearing children, we would have to choose an upper tailed test.
a) Since we want to test whether deaf children have higher visual acuity than hearing children. Hence, T=99.
b) Looking at the table, critical value is 85.
Since 99>85, reject H0.
Deaf
Hearing
Rank
Deaf
Hearing
1.15
1
1.33
2
1.43
3
1.64
4
1.65
5
1.73
6
1.75
7
1.95
8
2.03
9
2.17
10
2.3
11
2.45
12.5
2.45
12.5
2.64
14
3.14
15
3.23
16
Sum
99
37