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On Parametric Confidence Intervals for the Cost‐Effectiveness Ratio
Author(s) -
Gardiner Joseph C.,
Huebner Marianne,
Jetton James,
Bradley Cathy J.
Publication year - 2001
Publication title -
biometrical journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.108
H-Index - 63
eISSN - 1521-4036
pISSN - 0323-3847
DOI - 10.1002/1521-4036(200106)43:3<283::aid-bimj283>3.0.co;2-y
Subject(s) - confidence interval , mathematics , bonferroni correction , cdf based nonparametric confidence interval , coverage probability , tolerance interval , confidence distribution , statistics , credible interval , robust confidence intervals , interval (graph theory) , confidence region , interval estimation , parametric statistics , combinatorics
When comparing two competing interventions, confidence intervals for cost‐effectiveness ratios (CERs) provide information on the uncertainty in their point estimates. Techniques for constructing these confidence intervals are much debated. We provide a formal comparison of the Fieller, symmetric and Bonferroni methods for constructing confidence intervals for the CER using only the joint asymptotic distribution of the incremental cost and incremental effectiveness of the two interventions being compared. We prove the existence of a finite interval under the Fieller method when the incremental effectiveness is statistically significant. When this difference is not significant the Fieller method yields an unbounded confidence interval. The Fieller interval is always wider than the symmetric interval, but the latter is an approximation to the Fieller interval when the incremental effectiveness is highly significant. The Bonferroni method is shown to produce the widest interval. Because it accounts for the likely correlation between cost and effectiveness measures, and the intuitively appealing relationship between the existence of a bounded interval and the significance of the incremental effectiveness, the Fieller interval is to be preferred in reporting a confidence interval for the CER.