title: Accounting for between-study variation in incremental net benefit in value of information methodology.
abstract: Previous applications of value of information methods for determining optimal sample size in randomized clinical trials have assumed no between-study variation in mean incremental net benefit. By adopting a hierarchical model, we provide a solution for determining optimal sample size with this assumption relaxed. The solution is illustrated with two examples from the literature. Expected net gain increases with increasing between-study variation, reflecting the increased uncertainty in incremental net benefit and reduced extent to which data are borrowed from previous evidence. Hence, a trial can become optimal where current evidence is sufficient assuming no between-study variation. However, despite the expected net gain increasing, the optimal sample size in the illustrated examples is relatively insensitive to the amount of between-study variation. Further percentage losses in expected net gain were small even when choosing sample sizes that reflected widely different between-study variation.
authors: Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada. andy@andywillan.com
authors: Andrew R
authors: AR
authors: Willan
authors: Simon
authors: S
authors: Eckermann
mesh_terms: D002585:Cesarean Section / Q000191:economics; D003362:Cost-Benefit Analysis; D005260:Female; D006801:Humans; D018803:Models, Economic; D011247:Pregnancy; D016032:Randomized Controlled Trials as Topic / Q000191:economics / Q000379:methods*; D015203:Reproducibility of Results; D012107:Research Design; D018401:Sample Size; D014710:Version, Fetal / Q000191:economics