Peter Boatwright

Who they are

This page records the public professional record only. Nothing adverse is recorded and no motive is attributed.

The 2001 paper lists him at Carnegie Mellon University's Graduate School of Industrial Administration, and the 2005 paper at its Tepper School of Business. His wider career was not surveyed for this page, so nothing further is asserted. The record here is two papers and a correction note, and what they say about one grocer's data.

Key papers

Boatwright, P., & Nunes, J. C. (2001), 'Reducing Assortment: An Attribute-Based Approach', Journal of Marketing, 65(3), 50-63, doi:10.1509/jmkg.65.3.50.18330. Read at the level of the published abstract and through the 2005 paper that revisits it.

Borle, S., Boatwright, P., Kadane, J. B., Nunes, J. C., & Shmueli, G. (2005), 'The Effect of Product Assortment Changes on Customer Retention', Marketing Science, 24(4), 616-622, doi:10.1287/mksc.1050.0121.

The 2005 paper also cites a 2004 correction note to the 2001 article by Boatwright and Nunes. That note could not be read for this page.

Key ideas

The 2001 paper looked at a natural change at an online grocer, in which 94 per cent of categories had their item counts cut dramatically, particularly low sellers. Across the 42 categories examined, sales rose by an average of 11 per cent, sales rose in more than two thirds of them, and 75 per cent of households increased their overall spending. The authors then separated the cuts by what they removed. Customers reacted differently to the loss of sizes but welcomed the removal of redundant items, and brand and flavour were the attributes that mattered most. They also found that category sales depended on the total number of items offered.

The 2005 paper, led by Sharad Borle, used household records from the same grocer for every category in the store. It found the reduction lowered shopping frequency and purchase quantity, with the fall in frequency costing more, and that categories bought less often were hit hardest. It reports the 2001 study, together with the 2004 correction note, as finding no change in sales, an estimated rise of 1.5 per cent with a standard error of 1.4, and explains the gap by the 2001 analysis using a subset of categories and households that leaned towards frequently bought staples.

He is therefore on both sides of the question as the field studies posed it, and the two papers are best read together. The first shows that cutting clutter can be welcomed. The second shows that the answer changes when every category is counted. See assortment reduction and choice overload.

How to read the two papers together

The two papers answer different questions from the same grocer. The 2001 paper asked what happened to sales in the categories it examined, and it reported a rise. The 2005 paper asked what happened to households, and it reported that they ordered less often. A shop owner who reads only the first will conclude that cuts raise sales. One who reads only the second will conclude that they cost customers. Both conclusions are partial.

The correction note matters here. The 2005 paper cites a 2004 note to the 2001 article and describes the sales result as no change, a rise of 1.5 per cent with a standard error of 1.4, where the first publication gave 11 per cent. This page does not say what the note changed, because the note could not be obtained. It reports the two figures with the source of each, which is the position a reader can check.

What survives both papers is a point about which items to cut. The 2001 paper found that brand and flavour mattered most to customers, and that redundant items were not missed. That is a statement about what to protect, and it holds on either reading of the sales figure.

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