Calculating the Standard Deviation for a column

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05-18-2009

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Calculating the Standard Deviation for a column

Hi all,

I want to calculate the standard deviation for a column (happens to be column 3).

Does any know of simple awk script to do this?

Thanks

kylle345

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05-18-2009

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try this:

Code:

awk '{ lines=FNR; arr[lines]=$3; sum+=$3}
     END{ avg=sum/lines
     sum=0;
     for(i=1; i<=lines; i++)
      	{ v=arr[i]-avg;
      	  sum+= v*v
      	}
     printf("n=%d avg=%f  stddev=%f\n",
            lines, avg, sqrt( sum/( lines - 1) ) ) } ' filename

jim mcnamara

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