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Homework Help: Show how the variance decrease as degrees of freedom/sample size get bigger

  1. Apr 10, 2012 #1
    1. The problem statement, all variables and given/known data

    2. Relevant equations


    3. The attempt at a solution

    I'm confused actually how to go about this. Sounds very simple, but when i do what they suggest, 'first, find the variance of (n-1)s22

    i get larger variances rather than smaller, which makes no sense. should i be using the chart for this? (below)

  2. jcsd
  3. Apr 10, 2012 #2

    Ray Vickson

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    Science Advisor
    Homework Helper

    Since you don't tell us what the chart represents, it is impossible to tell if it is relevant or not; I suspect not.

    You are told that [itex] V = (n-1)S^2/\sigma^2 [/itex] has a Chi-squared distribution with (n-1) degrees of freedom. Do you know the variance formula for the Chi-squared distribution? (It is readily available.)

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