I am preparing a complex survey data for analysis. The survey involved a two-stage stratified cluster sampling. In the first stage, I have 7 strata and 14 sampling units and in the second stage I have 13 strata and 29 sampling units. I have made sure that there are at least 2 sampling units per sampling stratum. However, after declaring the survey design in Stata, the
svydescribe command yields strata that are duplicates of already existing strata but with single units. The following table depicts the Stata output after submitting the command
As can be seen from the table, in the second stage of sampling, unit/cluster 7 belongs to stratum 4. However, one observation which belongs to the same stratum and unit/cluster has been considered as belonging to a different stratum and unit/cluster. The same holds with stratum 7 and several other strata. What causes such problems and how are they handled?
Update: after serially issuing the commands
egen _svy_tag = tag( PSEUDOPSU PSUSTRATA SSU PSEUDOSSUST FPC1 FPC2), missing replace _svy_tag = _svy_tag | missing(NWEIGHT) list PSEUDOPSU PSUSTRATA SSU PSEUDOSSUST FPC1 FPC2 NWEIGHT if _svy_tag
as suggested by StasK in his comment below, I obtained the following output.