Nested grouped resampling

Source-derived companion to gp3ml 0.3.0 vignette nested-grouped-resampling.Rmd. R code blocks are omitted here; the Python companion script is under examples/nested-grouped-resampling.py.

Nested grouped-resampling workflow

Only outer-assessment predictions estimate the declared generalization target. Inner assessment partitions are used solely for tuning inside the outer analysis data.