[Gretl-users] Re: Request for cdemean()

On Wed, 13 Nov 2019, Sven Schreiber wrote: I would prefer not to go too far down the rabbit-hole here. IMO specialized variants of (re)scaling would be more appropriate for the "extra" addon. What Stefano says is clearly right: mere centering is not truly standardizing. Nonetheless, I think that what we're proposing (I guess, Ioannis and me) under the function stdize() might be defended as proper standardization (if that's what you want, and with variants regarding the standard deviation) plus a little bonus if what you actually want is to center a list of series. To elaborate on the last point, centering is a simple one-liner if you're working on a single series: series cy = y - mean(y) or a matrix: matrix cX = X .- meanc(X) but requires a slightly fiddly loop if you're working on a list: list cL = null loop foreach i L --quiet cL += genseries(sprintf("c%s", "$i"), $i - mean($i)) endloop So we overload the stdize() function with an option to let the user do the last thing with ease. We could, instead, assign this job to a separate function -- demean(), perhaps. But we're economists so we know about trade-offs: in this case a slight warping of the implied meaning of "stdize" versus further invasion of the function namespace (plus some mild code bloat). Allin