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    $\begingroup$ "To satisfy the CLT you need at least n=30." What is the basis for this statement? I can show cases where the distribution is non-normal yet $n$ much less that 30 gives good answers, and I can show cases where $n$ much greater than 30 is not sufficient. You can almost never have evidence that a population is normally distributed; indeed I doubt that's ever actually true. $\endgroup$ Commented Apr 16, 2013 at 3:46
  • $\begingroup$ @Glen_b I got it from the statistics course at the University of New South Wales where it is given as a "rule of thumb". $\endgroup$ Commented Apr 16, 2013 at 4:58
  • $\begingroup$ (Oh, hey. I taught stats there for a while, during my PhD, long ago.) It's a commonly-stated "rule" in a lot of the more cookbooky texts, but you shouldn't believe everything you're told. The actual support for it always seems to be absent. $\endgroup$ Commented Apr 16, 2013 at 6:35
  • $\begingroup$ @Glen_b Especially in a statistics course for an MBA in particular, I'm guessing! $\endgroup$ Commented Apr 16, 2013 at 6:37
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    $\begingroup$ @Glen_b Live & learn. $\endgroup$ Commented Apr 16, 2013 at 23:23