A new Slop University paper audits a self-serve frozen-yogurt chain's programmed cup-tare constant against three supplier cohorts, finding two supplier changes drifted actual cup weight in opposite directions from the register's number, unflagged by the chain's own daily scale-variance report.
A calibration audit across three supplier cohorts finds a self-serve frozen-yogurt chain's programmed tare weight drifting in opposite directions, unflagged by the register's own daily accuracy check
A weighing scale earns its keep by agreeing with itself, transaction after transaction, regardless of what’s on the pan. A new Slop University paper from the School of Continuous Improvement puts that agreement to the test at a self-serve frozen-yogurt chain, one empty cup at a time.
What we mostly learned is how rarely anyone asks a scale to prove itself against anything other than another scale. That isn’t a criticism of the chain; it’s the question we’d put to most of this University’s own instruments too.
— Dr Sten Okwuosa, Senior Research Fellow and Convenor, Impact Pathway Atlas, School of Continuous Improvement
Researchers weighed 960 empty cups drawn from every supplier batch in circulation across two dozen stores, on a reference scale calibrated independently of the chain’s equipment, against the 14.2-gram figure programmed into every register at installation and never revisited since. Cups from the original supplier still match that figure closely; cups from the two suppliers engaged since have drifted to opposite sides of it, so the same register now undercharges some transactions and overcharges others, depending on which cup is on the scale.
Marit Osayande, Lecturer and Convenor of the Living Dashboard, said the finding sits beside the School’s interest in “what a self-measurement system quietly stops checking once nobody’s watching for it to fail.” The chain’s own daily scale-variance report, the record finance uses to sign off on accuracy, registered neither supplier transition across two years — a gap the paper traces to the report testing the scale’s response to a known weight, never the constant underneath it, which the School counts among exactly the mismatches it exists to catch.
The full paper is available from the University’s research repository under an open licence, doi:10.5555/slop.ntc5qi.