Don't quote me on it but I get the feeling that if you select yourself as female, african american or hispanic, you have a better chance of getting into a survey than if you are male, white or asian, whom I feel are overrepresented in these studies. That being said, I'm a 25 year old Asian male and I'm content with the 1 or 2 survey opportunities I get daily. Dunno if it pays more to be younger or older.