variance (mg86506)

*To*: mathgroup at smc.vnet.net*Subject*: [mg86547] variance (mg86506)*From*: Kowalczyk-Schröder <HB-Kowalczyk-Schroeders at t-online.de>*Date*: Thu, 13 Mar 2008 04:35:07 -0500 (EST)

Greeting all I'm puzzled by the function "Variance". We can learn how to calculate variance from this page: <http://mathworld.wolfram.com/SampleVariance.html> http://mathworld.wolfram.com/SampleVariance.html. For example, calculate the sample variance of {1,2,3}. the average of {1,2,3} is 2, then the variance should be ((1-2)^2+(2-2)^2+(3-2)^2)/3=2/3. But mathematica gives that: In[10]:= Variance[{1.0,2.0,3.0}] Out[10]= 1. Why?? -- Best Wishes! Yours Sincerely Mathematica divides by (N-1) - like as far as I know all programs- This is correct if you have only a sample and not the whole. You can look up the reason for this and the derivation in some book about statistics. Sincerely, J. Schroeder ############################ Dr. Joerg Schroeder Bremen