Groups > comp.soft-sys.math.mathematica > #1962

Expected value of the Geometric distribution

From	"Tonja Krueger" <tonja.krueger@web.de>
Newsgroups	comp.soft-sys.math.mathematica
Subject	Expected value of the Geometric distribution
Date	2011-04-28 10:37 +0000
Organization	Steven M. Christensen and Associates, Inc and MathTensor, Inc.
Message-ID	<ipbg1f$ahf$1@smc.vnet.net> (permalink)

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Hi all,
I want to calculate expected value of diverse distributions like the Geometric distribution (for example).
As I understand this, the expected value is the integral of the density function *x.
But when I try to calculate this:
Integrate[(1-p)^k*p*k,k]
I get this as the answer:
((1 - p)^k p (-1 + k Log[1 - p]))/Log[1 - p]^2
Instead of: (1-p)/p.
I would be so grateful if someone could explain to me what I'm doing wrong.
Tonja
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Expected value of the Geometric distribution "Tonja Krueger" <tonja.krueger@web.de> - 2011-04-28 10:37 +0000
  Re: Expected value of the Geometric distribution Gary Wardall <gwardall@gmail.com> - 2011-04-29 11:30 +0000
  Re: Expected value of the Geometric distribution Stefan <wutchamacallit27@gmail.com> - 2011-04-29 11:32 +0000
  Re: Expected value of the Geometric distribution "Sjoerd C. de Vries" <sjoerd.c.devries@gmail.com> - 2011-04-29 11:32 +0000
  Re: Expected value of the Geometric distribution Peter Breitfeld <phbrf@t-online.de> - 2011-04-29 11:36 +0000

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