f 
20 
Percentage accuracy 
40 
60 
80 
100 
100 
] ——— grid squares 
o 
> = = — dot grids 
e. 807 
2 
c 
v 
o 
a 
60 
  
  
  
T 1 1 
60 80 100 
Percentage size of unit area 
Figure 4 Relationship between percentage error and percentage size of 
unit area: Given density of 169 observations per sample 
area. (1 ha. grid) 
0 
20 
Percentage accuracy 
40 
60 
80 
100 
Percentage error 
1003 : 
——— grid squares 
— — — dot grids 
80- 
60- 
407 
  
  
T Y' I 1 
40 60 80 100 
Percentage size of unit area 
  
Figure 5 Relationship between percentage error and percentage size of 
unit area: Given density if 324 observations per sample 
area. (0.5 ha. grid) 
833