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• ##### Nearly everyone in the Midwest and Northwest(0+ / 0-)

have low Vit. D levels. Does that mean most of them will get cancer?

Democrats promote the Common good. Republicans promote Corporate greed.

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• ##### Low vitamin D could make them more likely(0+ / 0-)

to get cancer, while higher levels might make it less likely.

It's statistical probability, not causality.

You can't go back and rewrite your past, but you can use your past to create your future. ~ Ray Lewis

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• ##### No(0+ / 0-)

You've transposed conditional probabilities, which is kind of a pet peeve of mine. "Most people who develop cancer have low Vitamin D" is not at all the same statement as "Most people who have low vitamin D develop cancer". The two probabilities involved are fractions that have the same numerator (the number of people who are both low on Vitamin D and develop cancer) but different denominators (respectively, the number of people who develop cancer and the number of people who are low on Vitamin D). In this case, the second denominator is a lot bigger than the first, so the chance of developing cancer if you're low on Vitamin D is way smaller than the chance of being low on Vitamin D if you develop cancer.

Another example: "more than half of welfare recipients are black" does not imply "more than half of black people are on welfare", a mistake I've seen a lot of people make (and note that even the first statement requires a fairly narrow definition of what constitutes being "on welfare").

Writing in all lower-case letters should be a capital offense

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