STATISTICAL METHODOLOGY FOR THE CONCURRENT ASSESSMENT OF INTERRATER AND INTRARATER RELIABILITY - USING GONIOMETRIC MEASUREMENTS AS AN EXAMPLE

Statistical methodology for the concurrent assessment of interrater an d intrarater reliability is presented. Application of the methodology is illustrated with an example of one therapist using two goniometers repeatedly to measure knee joint angles. Methods for estimating the co efficients, testing hypotheses, constructing confidence intervals, and computing sample size requirements are provided. In addition, the cal culation and clinical interpretation of the standard error of measurem ent (SEM) are discussed. It is recommended that (1) when both interrat er and intrarater reliability are being assessed, a repeated-measures design be used to take advantage of the increased precision gained by using all observations in the statistical analysis, and (2) appropriat e statistical tests, confidence intervals, and SEMs always be used in conjunction with the estimated reliability coefficients. [Eliasziw M, Young SL, Woodbury MG, Fryday-Field K. Statistical methodology for the concurrent assessment of interrater and intrarater reliability: using goniometric measurements as an example. Phys Ther. 1994;74:777-788.]