> See, the problem is there's almost no way to know if you're right. It turns out that this doesn't matter a lot of the time. You only notice because the adver

> See, the problem is there's almost no way to know if you're right. It turns out that this doesn't matter a lot of the time. You only notice because the advertising to you is bad - but once you can notice the money has already changed hands. I've worked with people who work on what is variously called "data zombies" or "data shadows" or "data doubles" and the problem is that: they often get it wrong and they do not care and pretend it's correct. This is doubly-concerning in the security realm (i.e. the NSA is only supposed to read data streams of non-Americans so they have a lot of incentive to produce classifiers that guess that things are not from the US).