A positive definite EEG contrast model permits every selected channel partial correlation between minus one and plus one under unrestricted common signal covariance

We test whether EEG voltage differences fix absolute channel partial correlation. The proof assumes a positive definite contrast covariance and unrestricted covariance of the missing common signal. For each selected pair, the same contrasts permit every partial correlation strictly between minus one and plus one. We give all positive definite covariance completions and a finite magnitude bound. An alpha band audit used 88 processed records from OpenNeuro ds004504 version 1.0.9 and a normalized contrast ridge of 0.001. All 15,048 record pairs allowed correlations below minus 0.992 and above plus 0.992 in separate completions. The package also gives an unsigned residual variance fraction. Its largest change across 24 shared reference conditions was 4.520e-13. All primary pairs passed separate Schur complement checks. Two fresh source downloads matched 128 saved windows. A full offline repeat matched every numerical result. The variance score depends on ridge, channel set, and earlier processing. The package preserves code, input matrices, source hashes, construction parameters, proof, figures, and repeat instructions.

EEG · covariance completion · partial correlation · voltage reference · contrast covariance · linear prediction · ridge regularization