If it is considered that at both information levels Scoring was 
restricted to very gross identifications, then the error rate (even 
the smaller rate of 25%) is high. The component-modifier method pro- 
vided & more stringent score than did the component method, in that 
both the component and modifier had to be correct for credit. Actually, 
scoring at the component-modifier level cannot be considered refined, 
for such scoring required identification only to the level of aircraft 
bomber, for example, omitting such finer discriminations as weight, 
number of engines, and whether or not it was a jet. If the component- 
modifier level of precision is desired, then the scoring cannot be con- 
sidered too stringent. 
Completeness of Information Extraction. Another aspect of photo- 
interpreter performance is the level of completeness of the information 
extracted. An interpreter may provide information that is perfectly 
accurate but it may be only a very small portion of the information to 
be obtained from a given photograph. The 'ground truth" key does not 
necessarily provide a fair reflection of extractability of information, 
in view of the fact that Picture quality may not permit the extraction 
of information on the objects actually photographed. To determine the 
extent of completeness of information extracted, an "expectancy key! was 
therefore devised. The 'expectancy key' reflects the total number of 
different components (or component-modifier combinations) accurately 
identified by any of the interpreters. A separate key was established 
for each photographed target, on the assumption that those objects cor- 
rectly identified by at least one interpreter are extractable. 
Table 1 
ACCURACY OF INFORMATION EXTRACTION IN PERCENT AT TWO 
INFORMATION LEVELS: COMPONENT AND COMPONENT-MODIFIER SCORES 
(FOR 16 EXPERIENCED PI's) 
  
  
  
  
  
Component Component-Modifier 
Target % right % wrong % right % wrong 
1 81 19 45 55 
2 75 25 56 Lh 
3 63 ST 56 lj, 
L 92 08 39 61 
5 66 3h 5l. l6 
6 Ol 16 Lo 51 
T 95 15 61 39 
8 65 35 16 5) 
9 64 36 ll 59 
Av. 75 25 50 20