reverse null/alternative hypotheses
- Null hypothesis in traditional superiority trial: treatments are similar until proven otherwise
- Null hypothesis in noninferiority trial: standard treatment superior to new treatment unless proven otherwise (unless proven equivalent)
- Predetermined equivalence range (): if results fall within this range, treatments considered equivalent
- Several approaches to determining
- Clinical notion of minimally important effect (subjective)
- Historical effect of active control in placebo trials
- Regulatory requirements
- Disease severity
- At times, one treatment can even be a bit worse than the other tx so long as it falls within the equivalence range
- Need different statistical analysis to determine superiority; may or may not be able to do so from same study depending on power
