[Gretl-users] Re: Request for cdemean()
Am 13.11.2019 um 10:33 schrieb Riccardo (Jack) Lucchetti:
On Wed, 13 Nov 2019, Stefano Fachin wrote:
>
> I think adding this to the GUI and extend it to operate on lists is a
> great idea. We should be careful about definitions, though -
> "standardize" means "center on the mean AND divide by standard
> deviation". Probably something more neutral like "scale" or
"rescale"
> is more suitable for a function which can be flagged to either center
> only or center + divide by s.d. (with or without d.f. correction)
I think Stefano has a point here; if I had to choose, I'd go by
"rescale".
IMHO, if a very generic name is chosen (which in principle is fine with
me) then I would suggest to put more thought and perhaps more
functionality into it. For example R's scale function
(https://www.rdocumentation.org/packages/base/versions/3.6.1/topics/scale)
allows to give obs-specific values to be subtracted (for centering) and
other obs-specific values for division (scaling as such).
Also I would like to mention a specific use case, namely recursive
recentering. Say x is a T-element column vector then for the wanted
result m we would have m[t] = x[t] - mean(x[1:t]). This could of course
be generalized to recursive standardization. (And I hear somebody
already screaming for rolling recentering :-)
thanks
sven