Searching question

An article in the Technology section of the Sydney Morning Herald this week focused on the increase in net searches following the death of Heath Ledger. Nothing unexpected in that, right? What about the statement that Yahoo reported that four of the fastest moving terms on its Buzz index were Ledger related - with "Heath Ledger" skyrocketing 110,285 per cent? And the next one - "A solid 62 per cent of those searches came from women, and the biggest search traffic came from New York, Arizona, and California" Yahoo said (as reported in the Herald). So - how do they know this? Okay, it's a matter of web statistic regarding number of hits and searches but how are they able to tell where the searches originate (possibly IP or service provider?) but what about the sex of the searcher. Yes, possible that Buzz is a service you have to be signed up for (and sex is part of the demographic information recorded) but if not ... where are they getting the stats from?