Re: st: Memory requirements for factor variables

[Partha Deb <partha.deb@hunter.cuny.edu>]

Federico - that is definitely a solution I hadn't thought of.  But, I do 
worry that the "simple" formula for the OLS estimate may not be optimal 
given the size of the dataset and potential scaling issues.  I'm still 
holding out for a slick answer from the Stata gurus, but I might end up 
using yours.  Thanks.
Partha


Federico Belotti wrote:
> Partha,
>
> I think there is no way to do that in stata. An alternative could be mata. Clearly, you have to write down the ado for your econometric model. An example using OLS is below.
>
> HTH
>
> Federico
>
>
> ******  do *******
> clear all
> set mem 10m
> set more off
>
> set seed 123456
>
> set obs 100000
>
> mata
> real matrix factor_reg(rows,cols,d1,d2,d3,d4,x,y) {
>
> 	D = J(rows,cols,0)
> 	for(i=1;i<=cols;i++) {
> 		for(j=1;j<=rows;j++) {
> 			if (d1[j]==i | d2[j]==i | d3[j]==i | d4[j]==i) D[j,i]=1
> 		}
> 	}
> 	X = x,D,J(100000,1,1)
> 	Y = y
> 	beta = invsym(X'X)*(X'Y)
> 	beta
> } 
>
> end
>
> gen x = rnormal()
> gen u = rnormal()
> gen int d = int(_n/1000)
> gen int d1 = int(_n/1100)
> gen int d2 = int(_n/1200)
> gen int d3 = int(_n/1300)
> gen int d4 = int(_n/1400)
>
> sum
>
> gen y = x + u
>
> describe,s
>
> regress y x i.d
>
> sum d
>
> tomata
> mata: factor_reg(100000,100,d1,d2,d3,d4,x,y)
>
> forvalues i=1/`r(max)' {
>
> gen byte Id`i' = (d1==`i' | d2==`i' | d3==`i' | d4==`i')
> }
>
> describe,s
>
> regress y x Id*
>
>
> exit
>
>
>
>
>   
--
Partha Deb
Professor of Economics
Hunter College
ph:  (212) 772-5435
fax: (212) 772-5398
http://urban.hunter.cuny.edu/~deb/

Emancipate yourselves from mental slavery
None but ourselves can free our minds.
	- Bob Marley

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