Simultaneous participant and stimulus generalization

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

Participant-and-stimulus generalization workflow

Cross-block rows that belong to only one held-out grouping dimension remain explicitly excluded. They are not silently reassigned to analysis or assessment.