approx. of binomial dist., help needed

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#650

From: YoungJun Lee
Date: Wed, 07 Oct 1992 02:58

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 The stat. book I have just says that
  "Binomial distribution with n trials and success probability p can be
   approximated by possion distribution(when n is large, p is very small, and
   np is of moderate magnitude" and normal distribution(when n is large and
   p is not too near 0 or 1)"

 What's large n ? 
 What's "the very small p" or "not too near 0 or 1"?
 What's np of moderate magnitude ?

 For instance, n = 1000 and p = 0.001, then is 1000 is large?,
 is 0.001  is very small  or not too near 0 ?
 is np (1000 * 0.001 = 1) of moderate magnitude?
 Should I approximate this by possion dist or normal ?

 Would you please give me an idea when I should use possion/normal dist.
 to approximate binomial distribution.

 Thanks,


 YoungJun Lee
 lee@cs.umn.edu

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From: lee@hecto.cs.umn.edu (YoungJun Lee)
Subject: approx. of binomial dist., help needed
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