Table 14.1
Example of overall, producer’s and user’s accuracies displayed in an error matrix, which tabulates the level of agreement between the thematic
class at a location in the image (rows) and the same location in the reference data (columns): overall accuracy = sum of the diagonal values divided by the
sum of all values; producer accuracy= column total divided by diagonal value for a specific category; and user accuracy = row total divided by diagonal
value for a specific category
Reference data
Row total
User accuracy
Seagrass cover
Sand
Deep
Mangrove
1–10 %
10–40 %
40–70 %
70–100 %
Image data
Seagrass cover
1–10 %
179
177
61
1
103
0
0
521
34 %
10–40 %
161
333
343
69
87
0
0
993
34 %
40–70 %
47
297
542
217
22
0
0
1,125
48 %
70–100 %
11
27
168
403
2
0
0
611
66 %
Sand
41
198
68
3
760
2
0
1,073
71 %
Deep
0
0
2
31
0
914
0
947
97 %
Mangrove
1
5
1
12
2
0
276
297
93 %
Column total
440
1,037
1,186
736
976
916
276
Producer accuracy
41 %
32 %
46 %
55 %
78 %
100 %
100 %
Overall accuracy
61 %
380
C. M. Roelfsema and S. R. Phinn