Hi folks,


I plugged the following set of numbers into Excel:


[600 470 170 430 300]


I found the mean (394), summed the numbers, divided by 5 to get variance (21704). I then did the square root to find stdev (147.32).


Using Excel or Wolfram Alpha's variance and stdev function give me differnt numbers, variance 27130 and stdev 164.71 respectively. Why? I believe I am following the equation as listed on Wikipedia, my stat text book, and the following page:


<http://www.mathsisfun.com/data/standard-deviation.html>


What am I missing?


Thank you for any help you can give!



Why does Excel/Wolfram come up with differnt stdev than I do?
The unbiased variance estimator normalizes by $n-1$, instead of $n$. This may be the difference you're seeing.


