This type of data is subject to so many biases there is no way to make it useful (in fact I'd argue that it is actually worse than useless, it's misleading and

This type of data is subject to so many biases there is no way to make it useful (in fact I'd argue that it is actually worse than useless, it's misleading and incorrect). I'd love to be corrected on this, so if you have ideas for gathering this kind of data in a useful/non-biased way I'd love to hear it.