Over at Good Math, Bad Math, Mark offers two entries for the Basic Concepts series:
Between those two, he tells you almost everything you need to know to lie with statistics. Or how to spot when somebody else is trying to lie to you with statistics, which is probably more useful.
Either way, they're well worth reading.
More like this
Here is a list of Basic Concept posts in Mathematics.
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Here is a list of Basic Concept posts in Computer Science and Logic.
We need more mathematical analysis to counter the claims of creationists, and here's a good one: Mark Chu-Carroll has started a new weblog titled Good Math, Bad Math