artcat: Sample-size calculation for an ordered categorical outcome

We describe a new command, artcat, that calculates sample size or power for a randomized controlled trial or similar experiment with an ordered categorical outcome, where analysis is by the proportional-odds model. artcat implements the method of Whitehead (1993, 12: 2257-2271). We also propose and...

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Bibliographic Details
Published in:The Stata journal Vol. 23; no. 1; p. 3
Main Authors: White, Ian R, Marley-Zagar, Ella, Morris, Tim P, Parmar, Mahesh K B, Royston, Patrick, Babiker, Abdel G
Format: Journal Article
Language:English
Published: United States 01.03.2023
Subjects:
clinical trial
evaluation
artcat
substantial-superiority trial
proportional-odds model
noninferiority trial
power
categorical variable
sample size
st0700
randomized controlled trial
ISSN:1536-867X
Online Access:Get more information
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Summary:We describe a new command, artcat, that calculates sample size or power for a randomized controlled trial or similar experiment with an ordered categorical outcome, where analysis is by the proportional-odds model. artcat implements the method of Whitehead (1993, 12: 2257-2271). We also propose and implement a new method that 1) allows the user to specify a treatment effect that does not obey the proportional-odds assumption, 2) offers greater accuracy for large treatment effects, and 3) allows for noninferiority trials. We illustrate the command and explore the value of an ordered categorical outcome over a binary outcome in various settings. We show by simulation that the methods perform well and that the new method is more accurate than Whitehead's method.
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ISSN:1536-867X
DOI:10.1177/1536867X231161934