The effect of measurement error on the test-retest reliability of repeated mismatch negativity measurements.

OBJECTIVE The aim was to study how the measurement error affects the repeatability of mismatch negativity (MMN) measurements. METHODS Event-related potentials (ERPs) to changes in sound frequency, location, intensity, duration, and composition were recorded five times during 1-3 weeks from 13 healthy adults using a multi-feature MMN paradigm. The accumulation of MMN was modeled empirically with respect to measurement error, and repeatability was estimated at 0.6-3.5-μV error levels. The analysis was made for the results in the single deviant conditions and their pattern (auditory discrimination profile). RESULTS At the single-subject level, the measurement error significantly affected the repeatability until it went below 9-17% of MMN peak amplitude. At the group level, the threshold was higher. Peak amplitude was generally the most repeatable parameter. Latency was superior when the error was moderate or small (<2-3 μV). CONCLUSIONS The measurement error affects the repeatability of MMN. In single-subject studies, it should not be neglected if it exceeds 10% of the MMN amplitude. The application of the auditory discrimination profile is recommended for future applications. SIGNIFICANCE The study provided quantitative results to support the discussion on improving the repeatability of the MMN measurements. They are expected to apply conditionally to other ERP measurements, too.