Grade division
Relative error 
correlation 
Variance-mean ratio 
Small error probability 
Level 1
0.01
0.90
0.35
0.95
Level 2
0.05
0.80
0.50
0.80
Level 3
0.10
0.70
0.65
0.70
Level 4
0.20
0.60
0.80
0.60
| Grade division | Relative error | correlation | Variance-mean ratio | Small error probability |
| Level 1 | 0.01 | 0.90 | 0.35 | 0.95 |
| Level 2 | 0.05 | 0.80 | 0.50 | 0.80 |
| Level 3 | 0.10 | 0.70 | 0.65 | 0.70 |
| Level 4 | 0.20 | 0.60 | 0.80 | 0.60 |