Abstract
The evaluation of test-retest reliability is crucial in biomechanical research, as it ensures the validity of experimental outcomes. A common measure of reliability is the intraclass correlation coefficient (ICC). This study aims to explore and compare methods for constructing confidence sets for the ICC of curve data. The ICC for curve data can be expressed as a so-called ICC curve, or as an integrated ICC. There are currently no guidelines for how to report the uncertainty in either case. We consider both confidence bands for the ICC curve, and confidence intervals for the integrated version of ICC. We conducted a simulation study covering different major shapes of ICC curves with different sets of parameters. These methods were also applied to assess test–retest reliability of knee kinematics during one-leg hop for distance landings. Our findings indicate that for the integrated ICC, two of the compared methods demonstrate distinct merits. Meanwhile, we recommend a rank-based bootstrap confidence band for the ICC curve.
