Interlaboratory variability of rotational chair test results II: Analysis of simulated data

Standardization of rotational chair testing across laboratories has not bee n achieved because of differences in test protocol and analysis algorithms. The Interlaboratory Rotational Chair Study Group was formed to investigate these differences, Its first study demonstrated significant variability in calculated results using actual patient data files, No estimation of accur acy could be made, however, because the "true" values of response parameter s were unknown. In this study we used simulated "patient" data files to fur ther explore the differences among analysis algorithms. We found a high deg ree of agreement and accuracy across laboratories using automated analysis of high signal-to-noise/low-artifact data for gain, phase, and asymmetry, V ariability increased significantly for the lower signal-to-noise ratio/high er artifact files, Operator intervention generally improved accuracy and de creased variability, but there were cases in which operator intervention re duced accuracy.