Monday, 15 December 2008

eBay and the AHP

I am an eBayer (or whatever the appropriate term is) to buy items for my stamp and postal history collection. From time to time, I have also sold on eBay. As such, one becomes aware of the size and complexity of the organisation that hs come to symbolise online trading in many countries. From time to time, once one has registered with eBay, one becomes aware of the data analysis carried out by the company's statisticians. I was emailed to ask if there was anything wrong, as I had not bought as much in the previous few months as I had in a similar period earlier -- in other words, my behaviour was outside their forecast limits.

Last week, I was invited to take part in an eBay survey and said yes. I am not sure what behaviour of mine had prompted this particular survey; it may have been another action that was outside their forecast limits, when I bought in a "Buy it now" sale; I invariably use auctions for my collecting.

There was something familiar about the structure of the questions, but I confess that I didn't recognise what it was until after I had answered the last questions and submitted the online survey. eBay was using the AHP (Analytic Hierarchy Process) to find out what I felt about some of the factors that vary from vendor to vendor. I was asked to imagine that I was considering an item at a particular price (30 British pounds) in a Buy it Now sale. That fixed one variable. Then I was asked to consider variations of delivery cost, photo and description quality, speed of communication, first in a ranking, and then by a succession of "Which do you prefer?" comparisons where two sales with differing profiles were offered. I think that I was reasonably consistent in my answers, although the example sales that were offered did not fit into my profile of eBay use. (For stamps, postage is seldom more than GBP1 within the UK and usually less than USD3 internationally; the examples offered had postage figures of up to GBP6.)

Wanting to find out more, I Googled for "eBay analytic hierarchy process" and came up with the answer that eBay does use AHP and ANP (network) and its use is mentioned in the citation of an INFORMS award to Thomas Saaty and in a publicity release put out by Decision Lens, the consultancy used by eBay for their AHP work.

It is strange to contribute to an OR study and only realise that you are doing so afterwards!

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