On Fri, 12 Oct 2001, Desmond Cheung (of Simon Fraser University,
Vancouver, BC) wrote:
> Is there any mathematical analysis to find how much the two peaks stand
> out from the other data?
Hard to answer, not knowing where you're coming from with the question.
Any answer depends on the model(s) you wish to entertain that would
generate a bimodal distribution. The more usual question, I believe,
is how much separation there is between the modes ("peaks"), which is
a horizontal distance, rather than how much the modes "stand out from the
other data", which rather sounds like a vertical distance.
One suspects that you might usefully begin by consulting the
literature on mixtures of normal distributions, or perhaps on mixtures
more generally.
> Is there any formulas to find the variance/deviation/etc that's
> similar to the unimodal distribution case?
Formulas for variance, std. deviation, etc., do not depend on the shape
of the distribution, except insofar as the functional form of the
distribution may lead to a simpler formula, as in the case of a binomial
distribution. Otherwise, if you want/need the variance (etc.) of a bimodal
distribution, use the same formulas you use for any other empirical
distribution.
Incidentally, you write "the unimodal distribution case" as though there
were only one unimodal distribution. There are lots.
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Donald F. Burrill [EMAIL PROTECTED]
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