Comparisons between superiority and non-inferiority trials
| Characteristics | Superiority trials | Non-inferiority trials |
| Null hypothesis | New treatment not superior to standard treatment/placebo | New treatment inferior to standard treatment |
| Alternative hypothesis | New treatment is better than standard treatment/placebo | New treatment non-inferior to standard treatment |
| Non-inferior margin | Not applicable | Predetermined |
| Sequential testing | Not possible | Can be performed |
| Significance level | P<0.05 (two-sided) | P<0.025 (one-sided) |
| Comparator | Standard treatment or placebo | Standard treatment (seldom placebo) |
| Possible outcomes | 1. New treatment superior (or inferior) to standard treatment/placebo 2. Inconclusive | See figure 1 |
| Subgroup analyses | Possible | Possible |