Bland–Altman plots, rank parameters, and calibration ridit splines

Roger Newson

London Stata Conference 2019 from Stata Users Group

Abstract: Scientists frequently work with pairs of alternative variables intended to measure the same quantity. Examples include measured and predicted disease prevalences in primary-care practices and marks awarded to student exam scripts by two different teachers. Statistical methods developed for use with such pairs of variables (A and B) may aim to measure components of disagreement between the variables (like discordance, bias, and scale differential), or they may aim to estimate one variable from the other (calibration). The Bland–Altman plot is the standard way of presenting a pair of alternative measures and allows us to visualize discordance, bias, and scale differential at the same time. However, it lacks parameters with confidence limits. The SSC packages somersd, scsomersd, and rcentile can be used to estimate rank parameters. They can measure discordance using Kendall's τa between A and B, bias using the mean sign and percentiles of A-B, and scale differential using Kendall's τa between A-B and A+B. For calibration (predicting A from B), we can use the SSC packages wridit and polyspline to define a ridit spline of A with respect to B. We can then plot the observed B and the predicted A (with confidence limits) against the ridit of B to create a continuous alternative to the standard decile plot commonly used for calibration.

Date: 2019-09-15
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

Downloads: (external link)
http://repec.org/usug2019/Newson_uk19.pdf presentation materials (application/pdf)
http://repec.org/usug2019/Newson_uk19.zip sample do-file (application/zip)

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:boc:usug19:01

Access Statistics for this paper

More papers in London Stata Conference 2019 from Stata Users Group Contact information at EDIRC.
Bibliographic data for series maintained by Christopher F Baum ().