Table 2 First example of confounding
| Unadventurous | Risk takers | Overall | |||||||||
| 5000 | 5000 | 10000 | |||||||||
| No A users | 40% use A | (Sum over unadventurous and risk takers) | |||||||||
| ↙ | ↘ | ↙ | ↘ | ↙ | ↘ | ||||||
| A | Not A | A | Not A | A | Not A | ||||||
| 0 | 5000 | 2000 | 3000 | 2000 | 8000 | ||||||
| No B users | No B users | 40% use B | 40% use B | (sum) | (sum) | ||||||
| ↙ | ↘ | ↙ | ↘ | ↙ | ↘ | ↙ | ↘ | ↙ | ↘ | ↙ | ↘ |
| B | Not B | B | Not B | B | Not B | B | Not B | B | Not B | B | Not B |
| 0 | 0 | 0 | 5000 | 800 | 1200 | 1200 | 1800 | 800 | 1200 | 1200 | 6800 |
| OR (within risk takers) = (800/1200)/(1200/1800) =1.00 | OR (overall, unadjusted) = (1000/1200)/(1200/6800) = 3.78 | ||||||||||