st: subpop() and over() with survey mean estimation using SDR weights

[Sam Schulhofer-Wohl <sschulh1.work@gmail.com>]

I get a syntax error message, r(198), when I try to estimate a survey
mean using both the subpop() and over() options and SDR weights.

I can't find any indication in the manual that this combination of
options and weights is not allowed. Also, for other kinds of weights,
there is no error. Some examples are below.

Has anyone run into this problem before? If so, any suggestions on how
to solve it? (Obviously, I can make a new variable that combines my
over() and subpop() categories, but in the particular analysis I'm
using, it would be more convenient to be able to use over() and
subpop() simultaneously.)

-- 
Sam Schulhofer-Wohl
Senior Economist
Research Department
Federal Reserve Bank of Minneapolis
90 Hennepin Ave.
Minneapolis MN 55480-0291
(612) 204-5484
wohls@minneapolisfed.org






*example of the error using SDR weights

. webuse ss07ptx, clear

. svyset

      pweight: pwgtp
          VCE: sdr
          MSE: off
    sdrweight: pwgtp1 pwgtp2 pwgtp3 pwgtp4 pwgtp5 pwgtp6 pwgtp7 pwgtp8 pwgtp9
               pwgtp10 pwgtp11 pwgtp12 pwgtp13 pwgtp14 pwgtp15 pwgtp16 pwgtp17
               pwgtp18 pwgtp19 pwgtp20 pwgtp21 pwgtp22 pwgtp23 pwgtp24 pwgtp25
               pwgtp26 pwgtp27 pwgtp28 pwgtp29 pwgtp30 pwgtp31 pwgtp32 pwgtp33
               pwgtp34 pwgtp35 pwgtp36 pwgtp37 pwgtp38 pwgtp39 pwgtp40 pwgtp41
               pwgtp42 pwgtp43 pwgtp44 pwgtp45 pwgtp46 pwgtp47 pwgtp48 pwgtp49
               pwgtp50 pwgtp51 pwgtp52 pwgtp53 pwgtp54 pwgtp55 pwgtp56 pwgtp57
               pwgtp58 pwgtp59 pwgtp60 pwgtp61 pwgtp62 pwgtp63 pwgtp64 pwgtp65
               pwgtp66 pwgtp67 pwgtp68 pwgtp69 pwgtp70 pwgtp71 pwgtp72 pwgtp73
               pwgtp74 pwgtp75 pwgtp76 pwgtp77 pwgtp78 pwgtp79 pwgtp80
  Single unit: missing
     Strata 1: <one>
         SU 1: <observations>
        FPC 1: <zero>

. set seed 12345

. gen mysubpop=(uniform()<.5)

. svy, subpop(mysubpop): mean agep, over(sex)
(running mean on estimation sample)

SDR replications (80)
----+--- 1 ---+--- 2 ---+--- 3 ---+--- 4 ---+--- 5
..................................................    50
..............................
invalid syntax
r(198);

*no error if I use only over()

. svy: mean agep, over(sex)
(running mean on estimation sample)

SDR replications (80)
----+--- 1 ---+--- 2 ---+--- 3 ---+--- 4 ---+--- 5
..................................................    50
..............................

Survey: Mean estimation           Number of obs    =    230817
                                  Population size  =  23904380
                                  Replications     =        80

         Male: sex = Male
       Female: sex = Female

--------------------------------------------------------------
             |                 SDR
        Over |       Mean   Std. Err.     [95% Conf. Interval]
-------------+------------------------------------------------
agep         |
        Male |   33.24486   .0470986      33.15255    33.33717
      Female |   35.23908   .0386393      35.16335    35.31481
--------------------------------------------------------------


*no error if I use only subpop()

. svy, subpop(mysubpop): mean agep
(running mean on estimation sample)

SDR replications (80)
----+--- 1 ---+--- 2 ---+--- 3 ---+--- 4 ---+--- 5
..................................................    50
..............................

Survey: Mean estimation           Number of obs    =    230817
                                  Population size  =  23904380
                                  Subpop. no. obs  =    115334
                                  Subpop. size     =  11954384
                                  Replications     =        80

--------------------------------------------------------------
             |                 SDR
             |       Mean   Std. Err.     [95% Conf. Interval]
-------------+------------------------------------------------
        agep |   34.17763   .0666841      34.04693    34.30833
--------------------------------------------------------------


*no error when using subpop() and over() with pweights
*(example from page 62 of [SVY])

. use http://www.stata-press.com/data/r12/nmihs, clear

. svyset

      pweight: finwgt
          VCE: linearized
  Single unit: missing
     Strata 1: stratan
         SU 1: <observations>
        FPC 1: <zero>

. generate nonblack = (race == 0) if !missing(race)

. svy, subpop(nonblack): mean birthwgt, over(marital age20)
(running mean on estimation sample)

Survey: Mean estimation

Number of strata =       3         Number of obs    =     4724
Number of PSUs   =    4724         Population size  =  3230403
                                   Subpop. no. obs  =     4724
                                   Subpop. size     =  3230403
                                   Design df        =     4721

         Over: marital age20
    _subpop_1: single age20+
    _subpop_2: single age<20
    _subpop_3: married age20+
    _subpop_4: married age<20

--------------------------------------------------------------
             |             Linearized
        Over |       Mean   Std. Err.     [95% Conf. Interval]
-------------+------------------------------------------------
birthwgt     |
   _subpop_1 |   3312.012    24.2869      3264.398    3359.625
   _subpop_2 |   3244.709   36.85934      3172.448    3316.971
   _subpop_3 |   3434.923   8.674633      3417.916    3451.929
   _subpop_4 |   3287.301   34.15988      3220.332    3354.271
--------------------------------------------------------------
Note: 3 strata omitted because they contain no subpopulation
      members.
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