62 
SYMPOSIUM PHOTO INTERPRETATION, DELFT 1962 
therefore is one measure of interpreter performance. The interpreter can mis- 
identify objects. Number of wrongs, therefore, is another measure of his per 
formance. Further, he can fail to respond where he should. Number of omits 
thus constitutes a third measure. In addition, two derivative measures were 
developed, one accuracy, the other, completeness. Accuracy is the proportion 
of correct to total responses an interpreter makes; it is the ratio of number of 
rights to number rights plus wrongs 
R 
R+W 
Completeness is the proportion 
of correct responses to total extractable information that is in fact extracted 
from a photograph; it is the ratio of number of rights to number of rights plus 
omits 
R 
R+Ö 
Accuracy and completeness as a function of mode 
The accuracy and completeness analysis was conducted separately for the 
two photo qualities, high and low. Within each quality four performance 
measures were analyzed separately, accuracy after six minutes of work, accu 
racy after thirty minutes of work and similarly completeness after six and 
thirty minutes of work. Table 2 shows the accuracy results for the four 
different modes of high photo quality. The comparison here is for each row. 
None of the differences is significant. Table 3 presents completeness results 
for the four different modes at high photo quality. Again the differences 
Table 2. Percent accuracy by photo mode for high photo quality 
Positive 
Negative 
Stereo 
Non-Stereo 
Accuracy 
Transparency 
Transparency 
Print 
Print 
Initial 
53 
53 
54 
47 
Final 
42 
38 
44 
40 
Mode differences are not significant. 
Table 3. 
Percent completeness by photo mode for high photo quality 
Positive 
Negative 
Stereo 
Non-Stereo 
Completeness 
Transparency 
Transparency 
Print 
Print 
Initial 
14 
10 
9 
10 
Final 
33 
27 
31 
30 
Mode differences are not significant. 
Table 4. 
Percent accuracy by photo mode for low photo quality 
Positive 
Negative 
Stereo 
Non-Stereo 
Accuracy 
Transparency 
Transparency 
Print 
Print 
Initial 
40 
41 
52 
39 
Final 
30 
33 
39 
37 
Mode differences are not significant.