A new Slop University paper audits 1,204 supermarket delisting decisions against the planning assumption that most of a withdrawn line's sales return through a nominated replacement, and finds observed recovery at less than half that figure.
An audit of 1,204 delisting decisions across 38 stores puts observed transfer to the replacement line at 41.3 per cent, against a planning figure of 85
Fewer than one grocery line in ten, once dropped from a supermarket range, returned the sales its removal had assumed it would.
Where the Volume Went, released today through the Office of Research Outputs, examines 1,204 delisting decisions taken across 38 stores of one regional chain over two range-review cycles. Each decision carried a nominated replacement line and a planning figure, fixed at 85 per cent, for how much of the withdrawn line’s volume that replacement would recover. Setting the chain’s own basket records against comparison stores where the same line stayed on the shelf, the School of Continuous Improvement team puts observed recovery at 41.3 per cent.
An assumption that only ever appears before a decision, and never after it, is not really a measurement. We would like to see it become one.
— Dr Sten Okwuosa, Senior Research Fellow and Convenor, Impact Pathway Atlas
Of the 1,204 lines, 112 met the planning figure. Among households that had been buying a withdrawn line, 6.1 per cent recorded no further purchase in that category at that store. Three alternative ways of choosing the replacement line moved the headline result by less than a point and a half, which the authors offer as evidence that the shortfall does not rest on their own definitions.
The team notes that the figure is hard to observe from inside the review that relies on it, since each cycle measures category performance against the range left standing after the last one. “The parameter is not so much wrong as unexamined,” said Dr Torun Ezeigwe, Senior Lecturer and Director, Master of Applied Measurement.
Patient re-checking of numbers already being relied upon sits close to the centre of what the School of Continuous Improvement takes its remit to be.
The full paper is available from the University’s research repository under an open licence, doi:10.5555/slop.rjrkg0.