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#1
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CORREL versus COVAR/STDEV^2.......why different?
Hi everyone,
If you list a column of any data, try to calculate CORREL for same column (i.e., against itself), you get 1 (which is correct). Now, try to calculate COVAR for that column (also against itself), and STDEV. then try to get Correlation using COVAR/(STDEV^2) you don't get 1?! What is the problem here? Shouldn't both get you 1? Thanks, Mike |
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#2
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CORREL versus COVAR/STDEV^2.......why different?
Look at the formulas in Help for these functions. Mathematically,
COVAR/STDEV^2 should give you (n-1)/n = (1-1/n), which is what I get with the test cases that I tried. If you use STDEVP instead of STDEV, you should get the results that you expected. Jerry "Mike" wrote: Hi everyone, If you list a column of any data, try to calculate CORREL for same column (i.e., against itself), you get 1 (which is correct). Now, try to calculate COVAR for that column (also against itself), and STDEV. then try to get Correlation using COVAR/(STDEV^2) you don't get 1?! What is the problem here? Shouldn't both get you 1? Thanks, Mike |
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#3
Posted to microsoft.public.excel.misc
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CORREL versus COVAR/STDEV^2.......why different?
Yes, thanks Jerry...
Jerry W. Lewis wrote: Look at the formulas in Help for these functions. Mathematically, COVAR/STDEV^2 should give you (n-1)/n = (1-1/n), which is what I get with the test cases that I tried. If you use STDEVP instead of STDEV, you should get the results that you expected. Jerry "Mike" wrote: Hi everyone, If you list a column of any data, try to calculate CORREL for same column (i.e., against itself), you get 1 (which is correct). Now, try to calculate COVAR for that column (also against itself), and STDEV. then try to get Correlation using COVAR/(STDEV^2) you don't get 1?! What is the problem here? Shouldn't both get you 1? Thanks, Mike |
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