Related Experiment Video
Updated: Sep 20, 2026

Isokinetic Robotic Device to Improve Test-Retest and Inter-Rater Reliability for Stretch Reflex Measurements in Stroke Patients with Spasticity
Published on: June 12, 2019
A comparison of two time intervals for test-retest reliability of health status instruments
Robert G Marx1, Alia Menezes, Lois Horovitz
1Sports Medicine and Shoulder Service Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021, USA. marxr@hss.edu
Abstract:
Studies of test-retest reliability for health-related quality of life instruments have used varying intervals between test administrations. There is no evidence available to aid in the selection of the time interval between questionnaire administrations for a study of test-retest reliability for health status instruments. We compared the test-retest reliability at 2 days and 2 weeks for four knee-rating scales and the eight domains of the SF-36. Seventy patients with disorders of the knee who were in a stable state were randomly allocated to repeat the questionnaires at either 2 days or 2 weeks. There were no statistically significant differences in the test-retest reliability (intraclass correlation coefficient and limits of agreement statistics) for the two time intervals.
Related Concept Videos
Reliability and Validity
Comparing the Survival Analysis of Two or More Groups
Comparing Experimental Results: Student's t-Test
Statistical Methods to Analyze Parametric Data: Student t-Test and Goodness-of-Fit Test
The Student's t-test is a statistical test that examines if there is a statistically significant difference between the means of two groups. This test is instrumental when dealing with data...
Longitudinal Research
Multiple Comparison Tests
It would be easy to compare two samples using a significance alpha level of 0.05. In other words, there is only one sample pair to be compared. However, it would be difficult to identify a significantly different sample if the number...
