Distant 50-second EEG samples have larger RMS posterior theta-to-alpha log-ratio changes than adjacent selected samples in 88 ds004504 v1.0.9 recordings

This study measured temporal agreement of a fixed posterior theta-to-alpha power ratio in 88 OpenNeuro ds004504 v1.0.9 recordings. The channels were P3, P4, Pz, O1, and O2. The analysis used log ratios and kept each person as the statistical unit. The primary early and late samples each contained 100 seconds of selected EEG. Their concordance correlation coefficient was 0.840, with a 95 percent bootstrap interval of 0.756 to 0.900. Approximate late-to-early agreement factors were 0.533 to 2.196. Nine people had more than a twofold change. A planned secondary comparison used equal 50-second samples. The distant-to-adjacent RMS log-change ratio was 1.761, with an interval of 1.488 to 2.073. The bootstrap used 10,000 samples and kept diagnosis group counts. Adjacent means adjacent selected epochs. Source boundary exclusions can interrupt a sample. These results concern one recording per person and one preprocessing path. They do not identify a cause or measure reliability between visits. Fresh extraction matched preserved features for three source recordings. A separate analysis matched all eleven scientific output files exactly. The package preserves data, source hashes, code, results, and reproduction instructions.

electroencephalography · EEG · theta-to-alpha ratio · temporal agreement · concordance correlation coefficient · Alzheimer disease · frontotemporal dementia · OpenNeuro