The report concerns a discussion of some methodological and statistical problems in testing color vision with the Nagel anomaloscope and an evaluation of records compiled during a period of four and a half years’ research work at the U. S. Air Force School of Aviation Medicine, Randolph Field, Texas. Following topics are dealt with: elimination of training effects and determination of the total number of readings required to detect specified minimum practical differences between individuals; application and frequency distribution of the anomalous quotient; determination of the normal matching range of mixtures and of comparison yellow; and test-retest reliability of the Nagel anomaloscope.
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Total number of readings (n) required to detect specified minimum practical differences (d) of average red-green mixture readings between individuals, on different values of d.
Minimum practical difference of individual average mixtures
Number of readings n required to detect a difference d or greater with a probability of
P=0.80
P=0.95
d
n
n
2.0
14
22
2.5
10
15
3.0
8
12
Table VI
Anomalous quotients (A.Q.) on normal averages for red (Rn) of 40 and 60, and the ratios for red/green (R/G) for various dial settings of the examinee (Rs).
Rs
A.Q. for Rn=40
A.Q. for Rn=60
R/G
0
∞
∞
0
5
17
63
0.1
10
8
29
0.2
15
4.7
18
0.3
20
3.2
12
0.4
25
2.3
9
0.5
30
1.7
6.6
0.7
35
1.3
5.0
0.9
40
1.0
3.8
1.21
45
0.75
2.9
1.61
50
0.56
2.1
2.17
55
0.40
1.5
3.06
60
0.26
1.0
4.62
65
0.15
0.57
8.13
70
0.05
0.20
23.33
73
0
0
∞
Table VII
Distribution by log anomalous quotients (log A.Q.) and by anomalous quotients (A.Q.) in 864 (97.8 percent) persons.
Total number of readings (n) required to detect specified minimum practical differences (d) of average red-green mixture readings between individuals, on different values of d.
Minimum practical difference of individual average mixtures
Number of readings n required to detect a difference d or greater with a probability of
P=0.80
P=0.95
d
n
n
2.0
14
22
2.5
10
15
3.0
8
12
Table VI
Anomalous quotients (A.Q.) on normal averages for red (Rn) of 40 and 60, and the ratios for red/green (R/G) for various dial settings of the examinee (Rs).
Rs
A.Q. for Rn=40
A.Q. for Rn=60
R/G
0
∞
∞
0
5
17
63
0.1
10
8
29
0.2
15
4.7
18
0.3
20
3.2
12
0.4
25
2.3
9
0.5
30
1.7
6.6
0.7
35
1.3
5.0
0.9
40
1.0
3.8
1.21
45
0.75
2.9
1.61
50
0.56
2.1
2.17
55
0.40
1.5
3.06
60
0.26
1.0
4.62
65
0.15
0.57
8.13
70
0.05
0.20
23.33
73
0
0
∞
Table VII
Distribution by log anomalous quotients (log A.Q.) and by anomalous quotients (A.Q.) in 864 (97.8 percent) persons.