Reliability and stability of contingent negative variation.

Reliability parameters of a test indicate the stability (and quality) of the test itself. Reliability coefficients greater than 0.70 suggest an attribute as being sufficiently stable over time to be characterized as a trait. Reliability parameters of contingent negative variation (CNV) amplitudes in 27 healthy individuals were determined using a test-retest design. CNV was recorded at Cz, with an interstimulus interval of 3 s, on 2 separate occasions: initial session and 10 days later. Correlation coefficients between the 2 recording sessions were 0.675 for the total-CNV (tCNV), 0.855 for the early component (iCNV), 0.631 for the late component (lCNV), and 0.420 for the post-imperative negative variation (PINV). Statistical retest parameters for Spearman Brown were 0.806 for tCNV, 0.922 for iCNV, 0.774 for lCNV, and 0.655 for PINV. The iCNV, more than the other parameters, remained stable over the period of 10 days. It is suggested that the described standardized CNV recording procedure ensures reproducible and stable results in healthy subjects.