## Support #318

### missing standard erroros Wave 3

100%

**Description**

Hello,

Some time ago I asked you about weights: https://www.understandingsociety.ac.uk/support/issues/106

Using the "subpop" with the variables' filters solved the issue of getting the standard errors for Wale 1; however, I cannot make it work in Wave 3.

I am running a cross-sectional analysis using this syntax:

svyset c_psu [pweight = c_indinub_xw], strata(c_strata)

svy, subpop(if male<2 & c_emp<2): logit c_emp male

where male and emp are 0-1 variables

Even if - as you can see - I restrict the variables to have valid values in all cases, I still don't get standard errors of this regression...

Any clues why subpop does not seem to work in Wave 3?

Am I doing something wrong?

Thanks!!

Carolina

### History

#### #1 Updated by Alita Nandi about 5 years ago

One of the reasons Stata does not produce standard errors when using svyset is that there are strata with only one PSU. I am not sure if this is the case, but if it is here are a couple of solutions.

One solution suggested by Stata is to use the option singleunit(). What this does is implement different methods of estimating standard error when this happens - you will need to decide which of these methods to use - certainty, scaled or centered. See Stata Help.

Another solution is to merge adjacent strata and continuing doing so until there are no single PSU strata.

#### #2 Updated by Alita Nandi about 5 years ago

**Status**changed from*New*to*In Progress***% Done**changed from*0*to*90*

#### #3 Updated by Carolina Zuccotti about 5 years ago

Dear Alita,

Thank you for your response!

Indeed, that is the problem: strata with single PSU.

Before (i.e. in wave 1) I used to solve it with the subpop specification only (added before the regression), so not sure why that does not work now.

In any case, the singleunit specification solves it.

Do you have any suggestions on which one to use? (or which one has been commonly used by researchers using UKHLS?).

Or any documentation that I could look at for this matter?

Many thanks in advance,

Carolina

#### #4 Updated by Alita Nandi about 5 years ago

At this point there is no guidance available as to which of the three options (certainty, scaled, centered) produce better estimates of the standard errors.

Alita

#### #5 Updated by Redmine Admin about 5 years ago

**Status**changed from*In Progress*to*Closed***% Done**changed from*90*to*100*