The BIS index is slow¶
The BIS index averages 15–60 s of EEG ending about 3 s before its stamp, with half its weight older than 30 s. It cannot time anything faster than about a minute.
| Status | established: shown on many cases, with a control. |
| Devices | BIS monitor |
| Variables | BIS index, BIS EEG |
What it means¶
Use features computed from the EEG itself for event timing; the index suits trends over minutes.
What is done about it¶
The bis_smoothing label gives each case's smoothing group.
Evidence¶
| Study | Date | Status | Summary |
|---|---|---|---|
| How the BIS index trails its EEG | 2026-10-13 | current | Modelling the BIS index as a lagged mix of EEG features shows a trailing average starting about 3 s after its EEG window ends: about 16 s long in half the cases (the 15 s smoothing setting) and 32–61 s in most others. Half the response weight is older than 30 s. |
| What a BIS-mimic project says about the index's smoothing | 2026-10-13 | current | The openeeg project reproduces the BIS index from the raw EEG and infers each case's smoothing setting: about 80% of its cases come out at 15 s. Its alignment cannot serve as a timing reference. |