Nice. But why did you ignore the very next sentence?



That's exactly what I've been saying. A self-selected sample is not representative of the entire population. 1000 women is too low a sample number when they're self-selected. So you see a bias in one way. The very next 1000 self selected women from the same area might have been biased in the opposite way, or biased even more towards weak women. The point is, in a non-random sample, you'll almost certainly see bias. There is no one reason for this.


This is the case with political poll. In epidemiology (which the current case is closer to, since channeling the OP is not an opinion, it is a genetic and metaphysical predisposition), it is not the strong opinions of respondents that leads to sample skewing.



But there is reason to know a systematic difference exists. Its not a matter of belief here. We know for a certain fact that this non-random population is showing characteristics markedly different from the norm.

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Your thought experiment is so stupid I'm at a loss for words. It is not remotely comparable because the probability of a coin landing heads or tails is decided at that very moment, and depends on the property of the coin, not the person tossing it! Further, it is astounding that you actually expect an equal number of heads and tails. The equal probability of the coin landing on either face doesn't translate to an equal number of actual events of either type occurring!

This is not a thought experiment. It is a thoughtless experiment. If this is the type of drivel you're going to come up with, please don't expect a response, and please don't whine if you don't get one.