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Tuesday, August 23, 2011

Algorithms and expensive books

A $24 million book, out of print, and about flies

I can't resist passing on a blogpost by eminent American biologist and researcher, Michael Eisen, about the strange discovery he made when he looked up an out-of-print textbook on Amazon.

A colleague in his lab logged onto, to buy an extra copy of Peter Lawrence's The Making of a Fly -- which, it seems, is the classic text on Drosophila (aka the common or garden fruit fly).

To his surprise, he found that he was going to have to dig deep into the petty cash to buy a new copy, as one was priced at $1,730,045.91 (+$3.99 shipping).

Yikes!  A million bucks for a textbook!

Eisen confesses he thought it was a prank -- but there were two copies for sale, each well over a million bucks.  Two jokes in tandem?  Surely not.

Even more mysteriously, when the page was reloaded the next day, the price had gone up.  Each was nearly $2.8 million!

The clue lay in the competition between the two sellers, who were quoting sums within five thousand bucks of each other.  Out came the calculator.  The copy offered by bordeebook was 1.270589 times the price quoted by pronath, a pattern that repeated itself as the price soared each day.  "So clearly," he says, "at least one of the sellers was setting their price algorithmically in response to changes in the other's price...

"Once a day profnath set their price to be 0.9983 times bordeebook's price.  The prices would remain close for several hours, until bordeebook "noticed" profnath's change and elevated their price to 1.270589 times profnath's higher price."

But why make a book more expensive than the competition? 

Eisen deduced that profnath had a copy of the book, but bordeebook did not.  Accordingly, bordeebook would want to make sure that their non-existent copy would always be a little more expensive, so that if they got an order, they could buy profnath's book, and cover costs when they sold it.

The next mystery was how long it would take to notice.  Eisen can even put a date on it: 19 April 2011, the day after the price peaked at $23,698,655.93 (+$3.99 shipping).

What triggered this sudden comprehension?  The joke reviewers, most probably.  Going into the current page for The Making of a Fly is an amusing experience, as the posters have had such a lot of fun.

John Taylor Kesler writes, for instance:

I was fortunate enough to buy this at the bargain price of $19,087,354 there must have been a sale because the next day it was listed at $23M. I was very pleased to find upon arrival that the book contained very useful information, however to be honest I was expecting a few more pictures for the price paid. I highly recommend this to all my associates, I have many acquaintances with children in only the best private schools who will be buying several copies. If the price has you worried, ask yourself the American question: "can you really put a price on good education?"

Explore the rest, if you have time to sit back and laugh.

And, oh yes, the book is now priced at $308.58


Anonymous said...

I've been thinking. If that is how it works, then I can buy a book cheaply
as follows. Suppose it is on the web at $10.00. I offer to SELL the book at
$10.10. Their algorithm adjusts their price to, sat $9.38. Not that I buy it
at that price. Instead I drop mine offered selling price to $9.48 and the
algorithm drops theirs to, say, $8.88 ... get the picture? Brian Easton.

Joan Druett said...

A jokester has also jumped onto the algorithm bandwagon, by offering the book, new, for $10,000! Judging by his seller name, he will use the proceeds as a deposit on a house.

Dale said...

Wonderful story!