How to find site's demographic?

[scuba]

I went to this one site and it said that 85% of the site's demographic is male, the majority of which are 18-34 year olds. My question is how do you find out this information for your site? Is it just an estimate they came up with or is there some specific way that you figure this out? I'm just curious of how I would do this once I get my site up.

[ewan]

They probably used Hitwise, they gather their data from ISPs, and also gather data from sample groups.

Hitwise, is not a cheap service, and is not that useful for really small sites, but if you have a big site, it will generate great stats for you and competitor sites.