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2175Re: [ai-geostats] Why degree of freedom is n-1

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  • Manuel Luis Ribeiro
    Aug 25, 2005
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      Hello Reza,
      i think it is because variance needs mean to be estimated. while you
      assume that every observation are i.i.d when you estimate the mean (so
      you divide by n), that's not true when you estimate variance, because
      1 observation depends on the mean you previously calculated (you can
      get the value of any observation from your sample, knowing all others
      and the mean value, right?)
      hum, hope it helps.
      PS: Please if i'm wrong somewhere in my explanation (i don't think so,
      but...), i would appreciate comments about it. Thanks
      Greetings, Manuel

      On 8/25/05, Reza Nazarian <rnazarian@...> wrote:
      > Dear Experts
      > Sorry may be the question is so basic .After searching my statistics books
      > to find an answer with no great success, could you please explain me why we
      > consider degree of freedom as n-1 in calculating variance. Thanks for your
      > kind advises.
      >
      >
      >
      > Very Best Regards
      > Reza Nazarian
      > Schlumberger Information Solutions
      > SONILS Oil Services Centre, Porto de Luanda, Angola
      >
      > (Via UK: +44 (0)207 576 6306
      > * rnazarian@...
      > http://www.sis.slb.com
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