Dear all,
I am using Stata version 9.2 (just updated it today!) and I am
re-running some analysis that I previously used in Stata 8.
The following command using version 8 code works, i.e. produces output
containing both regression coefficient estimates and standard errors:
. version 8
. svyset [pweight=newwgt], psu(psuid) strata(stratum)
. svyreg depvar $controls $dd $ddd
However, using the same data set and the following version 9 code
. svyset psuid [pweight=newwgt], strata(stratum)
. svy linearized: reg depvar $controls $dd $ddd
I get the following warning:
. Warning: variance matrix is nonsymmetric or highly singular
and output contains only regression coefficients (which exactly
correspond to those obtained from the version 8 command), but no
standard errors.
Does anyone know what changes have been implemented in Stata 9 as
opposed to Stata 8 concerning the Taylor linearized variance estimation?
Any help will be greatly appreciated.
Thanks in advance,
Elke
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