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The effect of outliers on confidence interval procedures for cost‐effectiveness ratios
Author(s) -
Indurkhya Alka,
Gardiner Joseph C.,
Luo Zhehui
Publication year - 2001
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.683
Subject(s) - confidence interval , statistics , percentile , outlier , robust confidence intervals , interval (graph theory) , nominal level , mathematics , medicine , computer science , econometrics , combinatorics
Cost‐effectiveness ratio (CER) is defined as the ratio of the difference in cost between a test and standard health care programme to the difference in benefit, respectively. Methods to obtain confidence intervals for CERs are either variants of Fieller's method (1954), or bootstrap methods. We study the effect of outliers in cost measures on the precision of confidence interval procedures for CERs. In particular the performance of the procedures under single and multiple case influential deletion diagnostics, respectively, are evaluated. Simulation studies suggest that the bias‐corrected percentile bootstrap procedure gives better precision and coverage under either diagnostic. Copyright © 2001 John Wiley & Sons, Ltd.