artcat: Sample-size calculation for an ordered categorical outcome

Ian White, Ella Marley-Zagar (), Tim P. Morris (), Mahesh K. B. Parmar (), Patrick Royston () and Abdel G. Babiker ()
Additional contact information
Ella Marley-Zagar: University College London
Tim P. Morris: University College London
Mahesh K. B. Parmar: University College London
Patrick Royston: University College London
Abdel G. Babiker: University College London

Stata Journal, 2023, vol. 23, issue 1, 3-23

Abstract: 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, Statistics in Medicine 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.

Keywords: artcat; sample size; power; clinical trial; randomized controlled trial; noninferiority trial; substantial-superiority trial; categorical variable; proportional-odds model; evaluation (search for similar items in EconPapers)
Date: 2023
Note: to access software from within Stata, net describe http://www.stata-journal.com/software/sj23-1/st0700/
References: Add references at CitEc
Citations:

Downloads: (external link)
http://hdl.handle.net/10.1177/1536867X231161934

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:tsj:stataj:v:23:y:2023:i:1:p:3-23

Ordering information: This journal article can be ordered from
http://www.stata-journal.com/subscription.html

DOI: 10.1177/1536867X231161934

Access Statistics for this article

Stata Journal is currently edited by Nicholas J. Cox and Stephen P. Jenkins

More articles in Stata Journal from StataCorp LLC
Bibliographic data for series maintained by Christopher F. Baum () and Lisa Gilmore ().