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Re: st: Questions about selmlog and svyselmlog


From   "Yu(Sophia) Zhang" <sophia.zhangyu@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Questions about selmlog and svyselmlog
Date   Thu, 21 Oct 2010 14:35:29 -0400

Dear Joao,

   Thanks for your patient explanation. I thought I understood what
you mean. But when I followed the rule and made sure that the
dependent variable has non-missing values for only one category, the
same error still showed up.

    What I understand the correct data structure about missing values
of depvar is like this:

   depvar    varlist, select ( depvar_m  =   varlist_m)....

    500          x                        1                      z
    456          x                        1                      z
    529          x                        1                      z
    601          x                        1                      z
    miss         x                        2                      z
    547          x                        2                      z
    408          x                        2                      z
    620          x                        3                      z
    599          x                        3                      z
    512          x                        3                      z
    miss         x                        3                      z
    miss         x                        3                     z

    So the depvar has non-missing values for category 1 only. It has
missing values for all the other categories (2 and 3).

    Would you please kindly correct me if I am wrong?

    I appologize to ask another question. If the command works, how
could save the variable lambda (Heckman correction term)?

    I appreciate your help a lot!

    Yu




On Wed, Oct 20, 2010 at 11:08 AM, Joao Ricardo F. Lima
<jricardofl@gmail.com> wrote:
> Dear Yu,
>
> the sintax of selmlog is:
>
> selmlog depvar varlist, select(depvar_m=varlist_m) [lee dmf(#) dhl(# [all]) etc
>
> depvar_m is your categorical variable, with more than 2 categories, oks?
>
> and
>
> depvar must have non-missing values for only one of theses categories.
>
> HTH,
>
> JL
>
>
>
> 2010/10/20 Yu(Sophia) Zhang <sophia.zhangyu@gmail.com>:
>> Dear Joao,
>>
>>  Thanks so much for your reply. The second question has been solved
>> following your suggestion.
>>
>>   For the first one, do you mean that across all categories ( which
>> are schools in my selection equation), only one category can have
>> non-missing values of dep var, and the other categories must have some
>> missing values of depvar? I deleted some values of depvar to meet this
>> requirement, but I still got the same error. Would you mind explaining
>> it in more detail?
>>
>>  Thank you so much!
>>
>>  Yu
>>
>> On Tue, Oct 19, 2010 at 7:03 PM, Joao Ricardo F. Lima
>> <jricardofl@gmail.com> wrote:
>>> Yu,
>>>
>>> About the first question:
>>>
>>> The vardep  of the income equation must have non missing values ONLY
>>> for one category.
>>>
>>> About the second:
>>>
>>> the svyselmlog was written to Stata 8. Then, try this:
>>>
>>> version 8: svyset [pweight = varw], psu(varpsu) strata(varstrat)
>>> svyselmlog vardep varindep , sel() meth() boot()....
>>>
>>> Hope this Helps,
>>>
>>> Joao Lima
>>>
>>>
>>> 2010/10/19 Yu(Sophia) Zhang <sophia.zhangyu@gmail.com>:
>>>> Dear statisticians,
>>>>
>>>>     I am now working on my dissertation and am stuck by a STATA command.
>>>> Basically, I want to run Heckman correction based on the multinomial logit
>>>> model. I am going to use the command selmlog. However, a strange error shows
>>>> up like this:
>>>>
>>>> Non-missing values of dependent variable for more than one outcome
>>>> variable _m* not found
>>>>
>>>>    I guess it might be associated with this statement in the help file:
>>>>
>>>> 1) In the output, selmlog adds to varlist a series of variables labelled
>>>> _m[depvar_m value], except for the dhl option
>>>>
>>>> 2) The outcome variable depvar is observed for only one value of depvar_m.
>>>> It is important that depvar should have missing values for any other value
>>>> of depvar_m.
>>>>
>>>>    But still cannot figure out what's wrong.
>>>>
>>>>    In addition, when I want to control for sampling weights by running the
>>>> command svyselmlog, I get another error:
>>>>
>>>> data not set up for the old survey estimation commands; use svyset under
>>>> version control or use the new svy prefix.
>>>>
>>>>   But there is no "svy: selmlog" command in STATA 11.....
>>>>
>>>>     I wonder if someone could kindly give me some hint for these two
>>>> problems. I have asked several people but no one were familiar with this
>>>> problem.
>>>>
>>>>     I appreciate your help very much.
>>>>
>>>>     Sincerely,
>>>>
>>>>     Yu
>>>>
>>>> *
>>>> *   For searches and help try:
>>>> *   http://www.stata.com/help.cgi?search
>>>> *   http://www.stata.com/support/statalist/faq
>>>> *   http://www.ats.ucla.edu/stat/stata/
>>>>
>>>
>>>
>>>
>>> --
>>> ---------------------------------------------------------
>>> João Ricardo F. de Lima
>>> Pesquisador A - Economia Aplicada
>>> Embrapa Semiárido
>>> e-mail: joao.ricardo@cpatsa.embrapa.br
>>> fone: +55 (87) 3862-1711 Ramal: 167
>>> home-page: www.cpatsa.embrapa.br
>>> ----------------------------------------------------------
>>>
>>> *
>>> *   For searches and help try:
>>> *   http://www.stata.com/help.cgi?search
>>> *   http://www.stata.com/support/statalist/faq
>>> *   http://www.ats.ucla.edu/stat/stata/
>>>
>>
>>
>>
>> --
>> Yu Zhang
>> PhD Candidate
>> Economics and Education
>> Teachers College, Columbia University
>>
>> *
>> *   For searches and help try:
>> *   http://www.stata.com/help.cgi?search
>> *   http://www.stata.com/support/statalist/faq
>> *   http://www.ats.ucla.edu/stat/stata/
>>
>
>
>
> --
> ---------------------------------------------------------
> João Ricardo F. de Lima
> Pesquisador A - Economia Aplicada
> Embrapa Semiárido
> e-mail: joao.ricardo@cpatsa.embrapa.br
> fone: +55 (87) 3862-1711 Ramal: 167
> home-page: www.cpatsa.embrapa.br
> ----------------------------------------------------------
>
> *
> *   For searches and help try:
> *   http://www.stata.com/help.cgi?search
> *   http://www.stata.com/support/statalist/faq
> *   http://www.ats.ucla.edu/stat/stata/

*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
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