Table 1 The Horsfall and Barratt (H-B) quantitative ordinal scale showing the disease severity ranges, midpoints and interval sizes (Horsfall and Barratt 1945)
H-B category | Disease severity range | Midpoint | Interval size |
|---|---|---|---|
1 | 0 | 0 | 0 |
2 | 0+-3 | 1.5 | 3 |
3 | 3+-6 | 4.5 | 3 |
4 | 6+-12 | 9.0 | 6 |
5 | 12+-25 | 18.5 | 13 |
6 | 25+-50 | 37.5 | 25 |
7 | 50+-75 | 62.5 | 25 |
8 | 75+-88 | 81.5 | 13 |
9 | 88+-94 | 91.0 | 6 |
10 | 94+-97 | 95.5 | 3 |
11 | 97+-100 | 98.5 | 3 |
12 | 100 | 100 | 0 |