According to just-released statistics from BookNet Canada, the shortlist announcement for the Scotiabank Giller Prize sparked a sales spike that averaged a 388% increase in weekly sales for the listed titles.

In the week ending October 14, 2007, A Secret Between Us by Daniel Poliquin saw the highest percent increase at 1200%, followed by Effigy by Alyssa York with 564%. Divisadero by Michael Ondaatje and The Assassin’s Song by M.J. Vassanji, already selling at a robust rate before the shortlist announcement, increased by 83% and 70% respectively, while Elizabeth Hay’s Late Nights on Air has seen a 22% bump in sales.

Quillblog doesn’t want to dampen the celebrations – any sales spike is a good sales spike – but interpreting this information requires a bit more analysis.

Although BookNet does not release sales figures, the percentages should be understood in light of the fact that pre-announcement sales for some of the books were quite small. Daniel Poliquin’s jump from a week of single digit sales to one in the low triple digits, explains the huge percentage increase for his book. York’s 564% increase similarly comes from a jump from low double digit to high double digit sales. Books from Hay, Vassanji, and Ondaatje all got smaller bumps from low triple-digits to mid triple-digits.

The percentage figures also don’t take into account the varying lengths of time each book has been on sale. Ondaatje’s Divisadero, for example, had much higher weekly sales right after it was released in the spring than it does now.

What was it that Mark Twain said about statistics?