[lapcat]

> The value of one person's anecdata is in fact not zero. I agree it's small.

It's less than zero. It's negative. Taking a very biased, unrepresentive anecedote and presenting it as positive evidence for some conclusion is fallacious and misleading. It's worse than presenting no data at all. You should have no confidence in a broad conclusion based on an anecdote.

> But if you ask 1000 people and they all say "I've heard of X but not of Y" or "I've heard of them both but heard more about X than about Y" then you have, in fact, got pretty good evidence that X is more famous than Y. Even if they're in the comments on an article about X, which of course I agree will give you a biased sample.

I couldn't disagree more. If you ask 1000 randomly selected people, that's pretty good evidence, but it's not good evidence if the sample is highly biased.