A statistic commonly used when referring to the brain drain is that 350,000 Canadians live in Silicon Valley. However, Dan Munro, a principal research associate in public policy at the Conference Board of Canada, recently researched the number and found through U.S. community surveys and the census that there are no more than 25,000 Canadians living there.

Mr. Munro called the 350,000 figure a “zombie statistic. … It just won’t die,” he said.

“This is a zombie fact, and it never dies,” said Agnes Quisumbing, senior research fellow at the International Food Policy Research Institute.

The deck is stacked against women in other ways, but the fact is, 70 percent of the people living in poverty are not women. Yet the statistic gets repeated and repeated — so much that people call it the "zombie stat."

Bradley exaggerates the "costs" a third way by unearthing a zombie statistic. He writes that "the dismissal rate from evidentiary exclusion is particularly high in drug cases…[O]ne study found as many as 30 percent of arrests lost due to search problems" (43-44. emphasis added). That 30 percent claim appeared in a 1982 National Institute of Justice study, and Justice White cited the figure in Illinois v. Gates. But I debunked that claim in my 1983 article.