Stata output files in surveys - stata

Question

I have some survey data which I'm using Stata to analyze. I want to compute means of one variable by group and save those means to a Stata file. My code looks like this:
svyset [iw=wtsupp], sdrweight(repwtp1-repwtp160) vce(sdr)
svy: mean x
I tried
svy: by grp: mean x
but that did not work. I could save each mean to a separate file by simply saying
svy: mean x if grp==1
but that's inefficient. Is there a better way?
Saving results to a file like one can use SAS ODS to capture results is also a need. I am not talking about the log here. I need the means and the associated group. I'm thinking
estimates save [path],replace
but I'm not sure if that will give me a Stata file or the group if I can figure out how to use by processing.

Answer 1

Here's a simpler approach that creates a data set of the displayed estimation results: estimated means, standard errors, confidence limits, z statistics, and p-values. svy: mean is called with the over() option, which does away with the need for the foreach loop and computes standard errors appropriate for subpopulation analysis. The estimation results are contained in the returned matrix r(table), which is converted by the svmat command to a Stata data set. While svmat maintains column names, it does not preserve row (group) names, so it is necessary to merge these in to the created data set.
set more off
use http://www.stata-press.com/data/r13/ss07ptx, clear
svyset _n [pw= pwgtp], sdrweight(pwgtp*) vce(sdr)
************************************************ *
* Set name of grouping variable in double quotes *
* in the next line. *
* ************************************************
local gpname "sex"
tempvar gp
egen `gp' = group(`gpname')
preserve
tempfile t1
bys `gp': keep if _n==1
keep `gp' `gpname'
save `t1'
restore
svy: mean agep , over(`gp')
matrix a = r(table)'
clear
qui svmat double a, names(col)
gen `gp'=_n
merge 1:1 `gp' using `t1'
keep `gpname' b se z pvalue ll ul
order `gpname'
save results, replace
list

Answer 2

Edited 10/28
This version contains legibility improvements and the outcome variable and saved datasets are specified in a local macro. Therefore the analyst need not touch the foreach block. Easier to write and read matrix subscript expressions are used instead of the el matrix function: thus m[1,1] instead of el("m",1,1).
sysuse auto, clear
svyset _n
************************************************ *
* Set names of grouping variable and results data *
* set in double quotes in the next line. *
* ************************************************
local yvar mpg // variable for mean
local gpname "foreign"
local d_results "results"
tempvar gp
gen `gp' = `gpname'
tempname memhold
postfile `memhold' ///
`gpname' n mean se sd using `d_results', replace
levelsof `gp', local(lg)
foreach x of local lg{
svy, subpop(if `gp'==`x'): mean `yvar'
matrix m = e(b)
matrix v = e(V)
matrix a = e(V_srssub)
matrix b = e(_N_subp)
matrix c = e(_N)
scalar gx = `x'
scalar mean = m[1,1]
scalar sem = sqrt(v[1,1])
scalar sd = sqrt(b[1,1]*a[1,1])
scalar n = c[1,1]
post `memhold' (gx) (n) (mean) (sem) (sd)
}
postclose `memhold'
use results, clear
list