Posterior theta-to-alpha ratios differed by more than twofold between selected 100-second EEG blocks in 9 of 88 ds004504 version 1.0.9 recordings

We tested posterior EEG theta-to-alpha power ratios in all 88 recordings from OpenNeuro ds004504 version 1.0.9. We compared 100 seconds of selected data at each record end. The ratio differed by more than twofold in 9 people. The fraction was 10.2%, with a Wilson 95% interval of 5.5% to 18.3%. The Spearman correlation was 0.867. The geometric mean late-to-early ratio was 1.082. With 10 seconds per end, 25 people had a difference above twofold. The package has the input features, source hashes, code, participant results, figures, and run instructions. Fresh source checks covered all 88 recordings with a separate FFT calculation. An offline rerun matched all numeric outputs byte for byte. This study measures change within one supplied recording per person. It does not establish arousal changes, agreement between sessions, or clinical accuracy.

electroencephalography · EEG · theta-to-alpha ratio · measurement agreement · within-record variation · OpenNeuro ds004504 · dementia