Re: st: Degrees of freedom formula for -svytab-

[Nick Winter <nw53@cornell.edu>]

Ironic.

It's been a while since I've mucked around under the hood with the -svy- 
commands (and with my -svr- commands).  True enough.

--Nick


At 05:23 PM 10/25/2004 +0100, you wrote:


> At 16:54 25/10/2004, Nick Winter wrote:
> > It looks to me like the -svy- commands do, in fact, return the df in e(df_r).
> >
> > This df is, in fact, e(N_psu) - e(N_strata). But you can just grab e(df_r).
> This is the case for -svymean-, -svyratio- and -svytotal- if the user 
> specifies the -complete- option. However, if the user specifies the 
> -available- option, then the number of PSUs can be different for different 
> parameters, and therefore the degrees of freedom is a vector (with the 
> same dimensions as the estimated parameter), and its value can be 
> calculated from the estimation results by the command
>
> matrix define dof = (e(_N_psu)-e(_N_str))'
>
> I have just referred back to the -parmest- update in which I introduced 
> the ability to handle vector degrees of freedom (dated 11 November 2002), 
> and, according to my records, it was Nick Winter who told me this (in his 
> email dated 6 November 2002). Thanks again to Nick for that.
>
> Best wishes
>
> Roger
--------------------------------------------------------
Nicholas Winter                           607.255.8819 t
Assistant Professor                       607.255.4530 f
Department of Government              nw53@cornell.edu e
308 White Hall            falcon.arts.cornell.edu/nw53 w
Cornell University
Ithaca, NY 14853-4601 

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