) 
CLASS 
No. of pixels 
in class 
Sample size 
No. of sample 
correctly 
classified 
% accuracy 
for each 
class 
95%> confidence 
limits by class 
(per cent) 
Weighting 
Water 
192 
60 
60 
100.0 
94 - 100 
0.0059 
Shallow Water 
31 
31 
31 
100.0 
90 - 100 
0.0009 
Woodland 
2067 
120 
106 
88.3 
82.4 - 94.3 
0.0631 
Heathland 
5430 
60 
50 
83.3 
73.1 - 93.6 
O.1656 
Upland Scrub 
10621 
60 
56 
93.3 
86.2 - 100.0 
0.3239 
Grassland 
11295 
60 
52 
86.7 
77.2 - 96.1 
0.3445 
Cropland 
2847 
60 
51 
85.0 
75.1 - 94.9 
0.0868 
Urban 
118 
60 
29 
48.3 
34.8 - 6l.8 
0.0036 
Fire Damaged/ 
Clear Fell 
Areas 
90 
60 
58 
96.7 
91.3 - 100.0 
0.0027 
Direct Shadow 
26 
26 
11 
42.3 
21.4 - 63.2 
0.0008 
TOTALS 
32727 
+ 59_ 
unclassi 
fied 
597 
0.9979 
+ 0.0021 
unclassi 
fied 
= 32786 = 1.000 
Overall map accuracy is the sum of the individual class accuracies, each being weighted 
according to the area of the map covered. 
Accuracy value = 87.5% and 95% confidence limits for this figure = 83.5 - 91.5% 
(See Snedecor and Cochran, 1977, p.527). 
TABLE 2 
RESULTS FROM SAMPLING GRANTOWN-ON-SPEY BLOCK FOR ACCURACY TESTING (BLOCK SIZE 194 x l69 = 32786 pixels)