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The superiority of a drug combination over each of its components
Author(s) -
Gibson Janet M.,
Overall John E.
Publication year - 1989
Publication title -
statistics in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.996
H-Index - 183
eISSN - 1097-0258
pISSN - 0277-6715
DOI - 10.1002/sim.4780081207
Subject(s) - sample size determination , type i and type ii errors , null hypothesis , statistics , mathematics , distribution (mathematics)
The requirement for approval of a combination drug treatment AB is its demonstrated superiority over each of its components A and B at their most appropriate dose levels. This has led to frequent use of a three‐group experimental design that permits separate testing of H o : AB ⩽ A and H o : AB ⩽ B. A type I error can occur if no true treatment effect is present in either or both of the contrasts. The sampling distribution for the larger of the two observed p ‐values, however, depends on whether a non‐null treatment effect is or is not present in one of the contrasts. We propose a strategy in which a conservative experiment‐wide type I error is achieved by defining the criterion for significance of the smaller observed treatment effect contingent on the magnitude of the larger observed treatment effect. We also discuss sample size requirements for the three‐group design.