The Shop Brand and the Name Brand Come Off One Line: Unimodal Production in 2,144 Product Classes, a Descending Grade Horizon, and the Re-Grading of Stock Sealed in 1988

There is no factory that makes the cheap one. The shop-brand tin, the entry-level machine and the budget tyre come off the same line as the dear version, and what separates them is a test and a label applied afterwards. We went looking for the second line in the industrial register and could not find it: not one plant we audited specifies a target below what it can already hold. If a single line makes everything, then a product class is one population and its grades are intervals cut into that population — which can be tested on shape alone, with no new instrument. Pooling end-of-line measurements in fixed physical units across 2,144 product classes, we find one mode in 2,109 of them, and no gap at any announced grade boundary, because a cut leaves none. The position of the cut is therefore a free parameter, and it has a history. Since 1954 the grade horizon has descended $0.42$ grade-widths per decade (95% CI $0.39$–$0.45$), while the production distribution has stood still. Stock sealed in 1988 and opened for this study was promoted two grades on re-assessment, its measurements unchanged. Blind, accredited assessors cannot separate the top bin from the bottom; told the grade, they can do nothing else. Nothing has been improved. The boundary was moved instead.