>> I had asked you how to calculate this and the variance early last
>> year.  One (I think the variance) was two-pass because of the need
>> for the average, but I thought the StdDev would work with the struct.

>Variance is just square of std. dev, no?

No !   Stdev is divided by count, Variance by (count - 1)

It was some time ago, but I thing there is a running function that 
can be calculated with one pass. I might be able to dig it up somewhere.
I had it in an excel sheet for learning purposes.

Andreas

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