biased and nonbiased.. ( god bless the google ;) )

Regards.

Ali

--- In firebird-support@yahoogroups.com, "unordained"
<unordained_00@c...> wrote:

> First of all, I'm a dork. STDDEV uses the mean, not the median,

and mean is the same as average. So

> you do have the aggregate for that. My stats prof. would be

ashamed.

>
> Divide by count(x) if you're considering the STDDEV to be relative

to the population (STDDEV of

> exactly the rows you're looking at), divide by count(x)-1 if

you're considering the STDDEV to be

> relative to a sample of the population (STDDEV of more than the

data you have -- extrapolating for

> the general case).
>
> -Philip
>
> ---------- Original Message -----------
> From: "Ann W. Harrison" <aharrison@i...>
>
> > Ali G?n wrote:
> > >
> > > if i remember correctly, STDDEV is:
> > >
> > > if(count(x)>1)
> > > sqrt ( sum((x-avg(x))*(x-avg(x))) / (count(x)-1) )
> > >
> >
> > or
> > > if(count(x)>1)
> > > sqrt ( sum((x-avg(x))*(x-avg(x))) / (count(x)) )
> >
> > Regards,
> >
> > Ann
> ------- End of Original Message -------