BACKGROUND: When applying classical tests of the null hypothesis in clinical trials, there has been considerable controversy over the choice between a one-sided versus a two-sided test. The choice between a one-sided and two-sided test still impacts on sample size calculations, assessment of study results by regulatory authorities, and publication of study results in academic journals. PURPOSE: To analyze the main elements in the controversy, and examine the procedures from both a Bayesian and classical viewpoint. METHODS AND RESULTS: Using a Bayesian decision framework, it is shown that there is no reason to double the p-value when moving from a one-sided to a two-sided test. Within the classical framework, it is shown that the doubling of the p-value results from a discontinuity due to testing a point null hypothesis. A three-decision rule, credited to Neyman or Wald, is presented that does not require the doubling of the p-value, and is consistent with a Bayesian approach. CONCLUSIONS: For most comparative clinical trials the three-decision rule is appropriate, and its use would abolish the controversy over one-sided tests.
%0 Journal Article
%1 Freedman2008
%A Freedman, Laurence S
%D 2008
%J Clinical trials (London, England)
%K BayesTheorem ClinicalTrialsasTopic DecisionSupportTechniques Humans Models ReproducibilityofResults Statistical
%N 6
%P 635-40
%R 10.1177/1740774508098590
%T An analysis of the controversy over classical one-sided tests.
%U http://www.ncbi.nlm.nih.gov/pubmed/19029216
%V 5
%X BACKGROUND: When applying classical tests of the null hypothesis in clinical trials, there has been considerable controversy over the choice between a one-sided versus a two-sided test. The choice between a one-sided and two-sided test still impacts on sample size calculations, assessment of study results by regulatory authorities, and publication of study results in academic journals. PURPOSE: To analyze the main elements in the controversy, and examine the procedures from both a Bayesian and classical viewpoint. METHODS AND RESULTS: Using a Bayesian decision framework, it is shown that there is no reason to double the p-value when moving from a one-sided to a two-sided test. Within the classical framework, it is shown that the doubling of the p-value results from a discontinuity due to testing a point null hypothesis. A three-decision rule, credited to Neyman or Wald, is presented that does not require the doubling of the p-value, and is consistent with a Bayesian approach. CONCLUSIONS: For most comparative clinical trials the three-decision rule is appropriate, and its use would abolish the controversy over one-sided tests.
%@ 1740-7745
@article{Freedman2008,
abstract = {BACKGROUND: When applying classical tests of the null hypothesis in clinical trials, there has been considerable controversy over the choice between a one-sided versus a two-sided test. The choice between a one-sided and two-sided test still impacts on sample size calculations, assessment of study results by regulatory authorities, and publication of study results in academic journals. PURPOSE: To analyze the main elements in the controversy, and examine the procedures from both a Bayesian and classical viewpoint. METHODS AND RESULTS: Using a Bayesian decision framework, it is shown that there is no reason to double the p-value when moving from a one-sided to a two-sided test. Within the classical framework, it is shown that the doubling of the p-value results from a discontinuity due to testing a point null hypothesis. A three-decision rule, credited to Neyman or Wald, is presented that does not require the doubling of the p-value, and is consistent with a Bayesian approach. CONCLUSIONS: For most comparative clinical trials the three-decision rule is appropriate, and its use would abolish the controversy over one-sided tests.},
added-at = {2023-02-03T11:44:35.000+0100},
author = {Freedman, Laurence S},
biburl = {https://www.bibsonomy.org/bibtex/24be9df63f045f0f6b610af5aa997a9c4/jepcastel},
city = {Gertner Institute for Epidemiology and Health Policy Research, Tel Hashomer 52161, Israel. lsf@actcom.co.il},
doi = {10.1177/1740774508098590},
interhash = {eccf0a68e38c41e181b92cdda9670ee1},
intrahash = {4be9df63f045f0f6b610af5aa997a9c4},
isbn = {1740-7745},
issn = {1740-7745},
journal = {Clinical trials (London, England)},
keywords = {BayesTheorem ClinicalTrialsasTopic DecisionSupportTechniques Humans Models ReproducibilityofResults Statistical},
month = {1},
note = {5060<m:linebreak></m:linebreak>JID: 101197451; RF: 33; ppublish;},
number = 6,
pages = {635-40},
pmid = {19029216},
timestamp = {2023-02-03T11:44:35.000+0100},
title = {An analysis of the controversy over classical one-sided tests.},
url = {http://www.ncbi.nlm.nih.gov/pubmed/19029216},
volume = 5,
year = 2008
}