AtlasSession 3L9: Variations in study designp.31–32
Non-inferiority and equivalence
- 5 earlier topics
- Test, null and alternate hypotheses
- Alpha error
- Tests, p-values, significance
- One- vs two-sided; equivalence
- Non-inferiority and equivalence
Fig. 1
Static two-point discrimination at 12 months, PCL nerve conduit minus autograft (mm; higher is worse)
Fig. 1. The likely range for new minus standard, 0.40 to 2.40 mm, against a line at 2.00 mm it must not cross (higher is worse). Verdict: can't tell yet.
- likely range
- 0.40 to 2.40 mm
- Allowed worse by
- 2.00 mm
- Verdict
- can't tell yet
Two-Curve Test Visualiser · First look
Level 1 · First look · Lecture 9 · p.31–32
Understand 'not meaningfully worse' and 'about the same' as different questions from 'better'.
Set a non-inferiority margin below the MCID or a symmetric equivalence zone, and state that non-inferiority uses one-sided and equivalence two-sided alpha and p-values.
Cheaper coffee (the step you are on)
It needn't taste better, just not noticeably worse than your usual brand.
A cheaper coffee needn’t taste better, just not noticeably worse than your usual. Same here: the tube’s likely range, 0.40 to 2.40 mm, is checked against a line 2.00 mm worse that it must not cross.