A yarn-dye house randomly draws three equivalent slices from one representative lot: one to fit the shade model, one to score and nudge it, one held back as the final judge. How should those slices be contrasted?

Three equivalent slices from one representative lot: one to fit, one to score and nudge, one held back as the final judge. Training fits, validation evaluates and tunes, test is the holdout. Those are three roles in one development cycle, not one role and not Chapter 6 A/B.