"...an estimated 29 percent of the athletes at the 2011 world championships and 45 percent of the athletes at the 2011 Pan-Arab Games said in anonymous surveys that they had doped in the past year.
"By contrast, less than 2 percent of drug tests examined by WADA laboratories in 2010 were positive...
"...Athletes at the events answered questions on tablet computers and were asked initially to think of a birthday, either their own or that of someone close to them. Then, depending on the date of the birthday, they were instructed to answer one of two questions that appeared on the same screen: one asked if the birthday fell sometime between January and June, and the other asked, “Have you knowingly violated anti-doping regulations by using a prohibited substance or method in the past 12 months?”"
On a separate note, does anyone know why Marin Cilic withdrew from the US Open? The US Open has issued statements on the withdrawals by Mardy Fish and Maria Sharapova, but not Cilic.