1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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
    TNtoZ.png


    2. Relevant equations

    XY0kG.png

    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)

    uhT2u.png
     
  2. jcsd
  3. Apr 10, 2012 #2

    Ray Vickson

    User Avatar
    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.)

    RGV
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Show how the variance decrease as degrees of freedom/sample size get bigger
  1. Sample Variance (Replies: 1)

Loading...