Four categories, one frozen protocol, and elasticities running from 0.50 to 1.03 — with a split between leave-on and rinse-off that survives the band check at three of four corners.

The four August categories split along one line: what stays on the skin answers price hard, what rinses off answers softly. Eye creams sit at the top — a 10 percent cut bought about 10 percent of rank, close to one-for-one — with serums just behind at 0.90. The two rinse-off categories cluster below: cleansers at 0.62, conditioner at 0.54, and conditioner is the cleanest symmetric case of the series, rewarding cuts and punishing increases in almost identical measure.

The band check decides what I'm allowed to call a finding. Three gaps survive it: eye creams sit demonstrably above both cleansers and conditioner on the cut side, and serums sit demonstrably above conditioner in both directions. Two near-misses are worth naming because they show how thin the line runs — serums against cleansers on cuts, and eye creams against conditioner on increases, each overlap by less than two hundredths. Those stay observations, whatever the point values suggest.

And the usual caveat carries extra weight this month: four categories make a pattern worth watching, not a law. The leave-on/rinse-off reading is a hypothesis the September batch — fragrances, beard oils, hand soaps — will stress-test from a different angle.