RELSA severity assessment and exploratory score forecasting

Overview

This skill computes reference-relative multivariate scores and exploratory ARIMA forecasts. It targets the equations and printed example of RELSA 0.0.1.9000 (commit e68e8451e8719ccc3600179f55900cd7254ede9d, current upstream at review), plus the published foRcast methodology. The Python forecast helper is an independent nonseasonal approximation, not an exact R port.

RELSA is the RMS of directional deviations divided by each variable's reference maximum deviation. Zero means no measured worsening in those directions; it does not establish normal welfare. One is a reference scale unit, not a universal endpoint or an upper bound. Different variables may attain their reference extrema in different animals or at different times, so the reference cohort need not contain a score of exactly one.

Forecasts estimate a score at a specified time, not time-to-endpoint or probability of death. Keep the approved study's observation schedule and humane endpoint criteria separate from these exploratory outputs. See Boundaries.