Michael,
what's the version of your Stata? Is it updated?
Joao Lima
2010/1/7 Michael Begg <[email protected]>:
> Hi,
>
> I am working on a data from a 2 stage survey design with 2 stratum. When I calculate the mean of hhsize, the standard error is missing as shown below.
>
>
> svy: mean hhsize
> (running mean on estimation sample)
>
> Survey: Mean estimation
>
> Number of strata = 2 Number of obs = 5964
> Number of PSUs = 194 Population size = 16041309
> Design df = 192
>
> --------------------------------------------------------------
> | Linearized
> | Mean Std. Err. [95% Conf. Interval]
> -------------+------------------------------------------------
> hhsize | 4.656919 . . .
> --------------------------------------------------------------
> Note: missing standard error because of stratum with single
> sampling unit.
>
>
> As per http://www.stata.com/support/faqs/stat/stratum.html, I check my data using svydes hhsize and find the following:
>
> Survey: Describing stage 1 sampling units
>
> pweight: weight
> VCE: linearized
> Single unit: missing
> Strata 1: rural
> SU 1: psu
> FPC 1: npsu
> Strata 2: <one>
> SU 2: ssu
> FPC 2: nssu
> Strata 3: <one>
> SU 3: hh
> FPC 3: nhh
>
> #Obs with #Obs with #Obs per included Unit
> #Units #Units complete missing ----------------------------
> Stratum included omitted data data min mean max
> -------- -------- -------- -------- -------- -------- -------- --------
> 1 136 0 4241 0 16 31.2 39
> 2 58 0 1723 0 16 29.7 32
> -------- -------- -------- -------- -------- -------- -------- --------
> 2 194 0 5964 0 16 30.7 39
> ------------------
> 5964
>
> Why are the standard errors missing when both stratum have more than one sampling unit and there are no missing observations.
>
> Thanks for your help
>
> Cheers
>
> Michael
>
>
> *
> * For searches and help try:
> * http://www.stata.com/help.cgi?search
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
>
--
----------------------------------------
Joao Ricardo Lima, D.Sc.
Professor
UFPB-CCA-DCFS
Fone: +5538387264913
Skype: joao_ricardo_lima
----------------------------------------
*
* For searches and help try:
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* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
