Table 3 Illustration of the effect of collapsing exposure categories
X1=1 | X1=2 | ||||||||
|---|---|---|---|---|---|---|---|---|---|
X 2 | Diseased | Not diseased | Total | RR | X 2 | Diseased | Not diseased | Total | RR |
1 | 20 | 380 | 400 | 1.0 | 1 | 5 | 95 | 100 | 1.0 |
2 | 30 | 270 | 300 | 2.0 | 2 | 20 | 180 | 200 | 2.0 |
3 | 30 | 170 | 200 | 3.0 | 3 | 45 | 255 | 300 | 3.0 |
4 | 20 | 80 | 100 | 4.0 | 4 | 80 | 320 | 400 | 4.0 |