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#1
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How is StdDev calculated?
The StdDev gave number much smaller than the squre root of sum of square of
deviation from the mean. How is it calculated? |
#2
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How is StdDev calculated?
Type "stdev" in Excel HELP
You'll get a full decription -- Kind regards, Niek Otten Microsoft MVP - Excel "xyw" wrote in message ... | The StdDev gave number much smaller than the squre root of sum of square of | deviation from the mean. How is it calculated? |
#3
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How is StdDev calculated?
=STDEV(data) should be =SQRT(DEVSQ(data)/(COUNT(data)-1) which is supposed to
be less than DEVSQ(data) by a factor of 1/SQRT(COUNT(data)-1). If you mis-stated the situation, and STDEV(data) is instead less than SQRT(DEVSQ(data)/(COUNT(data)-1), then I will guess that you are using Excel XP (2002) or older, and your data has a small CV (coefficient of variation, also known as RSD -- relative standard deviation). Older versions of Excel used a mathematically correct, but numerically unstable algorithm that could give numerically incorrect results with a small CV or a very large n. It is had to be more specific without more information about your particular case. Jerry "xyw" wrote: The StdDev gave number much smaller than the squre root of sum of square of deviation from the mean. How is it calculated? |
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