[Genome] Standard deviation of counts

[Hiram Clawson]

standard deviation = sqrt(variance)

variance = (sum(values squared) - ((sum(values)*sum(values))/N) ) / (N - 1)

In the C code it looks like:
double stddev = 0.0;
double variance = 0.0;
if (dataPoints > 1)
   {
   variance = (sumSquares - ((sumData*sumData)/dataPoints)) /
                 (double)(dataPoints-1);
   if (variance > 0.0)
      stddev = sqrt(variance);
   }

See also: http://en.wikipedia.org/wiki/Standard_deviation

--Hiram

Jeffrey Rosenfeld wrote:
> Hi,
> 
> For the phastCons tables, you give the sum of squares value.  How can 
> this be used to calculate the standard deviation?
> 
> Thank You,
> 
> Jeffrey Rosenfeld