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MathGroup Archive 2000

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Mean of Geometric and Negative Binomial distributions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg24066] Mean of Geometric and Negative Binomial distributions
  • From: "Gareth J. Russell" <russell at cerc.columbia.edu>
  • Date: Thu, 22 Jun 2000 01:01:58 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Dear Group,

Can anyone tell me why Mathematica returns (1-p)/p for
Mean[GeometricDistribution[p]] and n(1-p)/p for
Mean[NegativeBinomialDistribution[p]], when all sources I have to hand (such
as CRC Standard Mathematical Formulae) give these as 1/p and n/p
respectively?

The variance expressions agree with CRC, it's just the means that are
different.

Thanks,

Gareth
 
==================================================
Dr. Gareth J. Russell

NEW ADDRESS and E-MAIL FROM 1ST SEPTEMBER, 1999

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OLD ADDRESS (AND STILL MY EMPLOYERS)

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==================================================




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