Table 1
Potential outcome notation for additive and multiplicative causal effect measures for continuous and binary outcomes
| Type of outcome | Scale | Potential outcome notation | Effect measure | Example interpretation |
| Continuous | Additive |
| Causal mean difference | ‘An average increase in systolic blood pressure by 10 mm Hg’ |
| Multiplicative |
| Causal mean ratio | ‘An average increase in systolic blood pressure by a factor of 1.1’ or ‘by 10%’ | |
| Binary | Additive |
| Causal risk difference | ‘An average increase in the risk of stroke by 5 percentage points’ |
| Multiplicative |
| Causal risk ratio | ‘An average increase in the risk of stroke by a factor of 1.5’ |