A funny thing happened after Google's new privacy policy was announced last week

. When people started checking what Google knows about them on Ad Preferences Manager---that's the profile of you they build by watching your movements on the Web, so they can tailor ads accordingly---young women began reporting

that actually, Google had aged them quite a bit

. And had thought they were dudes. One young lady of our acquaintance is believed by the Ad Preferences genie to be a "65+" male. Why? Well, as Kashmir Hill at Forbes points out

, the way Ad Preferences works is by placing a cookie on the computer you happen to be using at the moment. The cookie records the sites you visit, each of which has certain user demographic information, like percentage of male and female visitors, age range, etc. ascribed to it by Google (though where they get that information, and how accurate it is, is not clear). Then Ad Preferences combines all the demographics of those sites to get your special blend of age, gender, interest in power tools, etc. Your Ad Preferences profile is not based on your Google profile---what you search, what you talk about in your Gmail, what you upload to YouTube. It's based just on what you visit. Additionally, each computer you use gets its own cookie, so it's not like the Ad Preference readout you'd see if you checked it right now

encompasses all the browsing you do. Whatever computer you check your Ad Preferences on will have a sense of you that's based on what you browse on that computer. So if you're checking it on your work machine, and you read and write about science and tech, for instance, chances are the mostly-male statistics assigned to those fields will dominate your profile. The woman who was mistaken for a 65-year-old man works at a law school, in fact; perhaps spending all day on law sites and databases is an activity dominated older males. You're probably most likely to get an accurate description of yourself if you visit mainly sites that are associated with your demographic. If you read stuff that other people of your age and gender usually don't, you're going to be pigeonholed as whatever is dominant on those sites. But this whole thing has got us wondering how accurate sites' demographic information really is. How do they come up with it? Are there a bunch of stealth females on tech sites who aren't getting recognized? As for me, it stuck me in the right age range (25-34), but thinks I'm male, with a penchant for reading oil and gas business sites and an interest in computers and electronics, which is a pretty small slice of my web-reading pie. What does your Ad Preferences readout

say about you? And is it right? [via Forbes

]