In general, you don't use the -if option with survey commands. That is
equivalent to saying the observations excluded by the -if statement are not
in the population sampled from. Use either the by option or subpop();
Personally, I prefer a table showing all values, that is make "producti" a
row variable of a table with -svytab-.
Bryan Sayer
Statistician, SSS Inc.
[email protected]
-----Original Message-----
From: Theodoropoulos, N. [mailto:[email protected]]
Sent: Monday, October 21, 2002 2:46 PM
To: [email protected]
Subject: st: svy commands
Dear statalisters,
I am using the survey commands in Stata to find some means. I have removed
all the stratums in which one psu (primary sampling unit) is detected. I
check that there is no stratum with one psu for all my variables by using
the svydes command.
I don't have problems to get the invididual means for the individual
variables "general" and "producti". However when i want to find the mean of
the "general" variable given that "producti" variable is equal to zero i get
the message that a stratum with one psu is detected. The "general" variable
is continuous, and the "producti" variable is binary.
Any hints will be highly appreciated.
Thanks in advance.
Here is a copy of the output that i get.
svymean general
Survey mean estimation
pweight: empwt_nr Number of obs =
1727
Strata: newstr1 Number of strata =
44
PSU: newpsu1 Number of PSUs =
162
Population size =
1200.4609
----------------------------------------------------------------------------
--
Mean | Estimate Std. Err. [95% Conf. Interval] Deff
---------+------------------------------------------------------------------
--
general | 4.156863 .0044976 4.147957 4.16577 2.432631
----------------------------------------------------------------------------
--
. svymean producti
Survey mean estimation
pweight: empwt_nr Number of obs =
1727
Strata: newstr1 Number of strata =
44
PSU: newpsu1 Number of PSUs =
162
Population size =
1200.4609
----------------------------------------------------------------------------
--
Mean | Estimate Std. Err. [95% Conf. Interval] Deff
---------+------------------------------------------------------------------
--
producti | .3359512 .0475784 .2417331 .4301693 17.51394
----------------------------------------------------------------------------
--
. svymean general if producti==0
stratum with only one PSU detected
r(460);
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