Related Experiment Video
Updated: Aug 11, 2026

A Protocol of Manual Tests to Measure Sensation and Pain in Humans
Published on: December 19, 2016
Ridit scores for analysis and interpretation of ordinal pain data
1Clinical Research Division, Fred Hutchinson Cancer Research Center, and Department of Statistics, University of Washington, Seatttle 98109, USA.
Abstract:
Pain studies frequently generate outcome data in the form of ordered categorical responses. Measurement properties of such ordinal variables do not permit straightforward numeric treatment, yet purely categorical (nominal) procedures fail to incorporate the ordered nature of the pain response. This paper describes analysis of ordered categorical data by means of ridit analysis, a simple, yet statistically valid and efficient, technique that yields a highly intuitive interpretation of a treatment effect. The mean ridit comparison of two treatments estimates the probability that a randomly-selected patient from one will have higher pain than a randomly-selected patient from the other. Ridit analysis is illustrated with two examples from a clinical trial involving patients with painful bony metastases subsequent to hormone-refractory prostate cancer.
Related Concept Videos
Ordinal Level of Measurement
Data measured using an ordinal scale are similar to nominal scale data, but there is one major difference. The ordinal scale data can be ordered. An example of ordinal scale data is a list of the top five national parks in the...
Ratio Level of Measurement
A set of data measured using the ratio scale takes care of the ratio problem and provides complete information. Ratio scale data are like interval scale data, except they have a zero point and ratios can be calculated. For...
Percentile
Ranks
Friedman Two-way Analysis of Variance by Ranks

