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Re: st: help needed on discrete-time hazard model


From   "Lili Yan" <lyan16@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: help needed on discrete-time hazard model
Date   Thu, 18 Oct 2007 14:24:35 -0400

Hi Thomas,

Thank you very much for helping out!
I know little about this model, so I thought the two zeros indicate
something wrong in the data. The e(N) is correct, which I am sure.

Here are some codes of setting up the data. I need explain first that
smok_stat = 1 for SSS, 2 for SSQ, 3 for SQS and 4 for SQQ.
................codes start here................

gen smk_time=3 if smok_stat==1 | smok_stat==2;
replace smk_time=2 if smok_stat==3 | smok_stat==4;

gen cessyear=2004 if smok_stat==1;
replace cessyear=2004 if smok_stat==2;
replace cessyear=2003 if (smok_stat==3 | smok_stat==4);

expand smk_time;
bysort uniqid: gen seqvar=_n;
bysort uniqid: gen qtsmok=smok_stat>1 & _n==_N;

bysort uniqid: gen evntyear=cessyear;
replace evntyear=2002 if seqvar==1;
replace evntyear=2003 if seqvar==2;
drop cessyear;
rename evntyear cessyear;

gen wave=1 if cessyear==2002;
replace wave=2 if cessyear==2003;
replace wave=3 if cessyear==2004;

gen wave1=wave==1;
gen wave2=wave==2;
gen wave3=wave==3;

svy: logit qtsmok male age married white mdrt_educ high_educ incm_mdrt
incm_high canada rPSPPPi wave2 wave3, noconstant
...............codes end here..........

Here is the output:

..............output starts here................
Survey: Logistic regression

Number of strata   =        26                  Number of obs      =      5642
Number of PSUs     =      5642                  Population size    = 5773.9291
                                                Design df          =      5616
                                                F(  12,   5605)    =    166.35
                                                Prob > F           =    0.0000

------------------------------------------------------------------------------
             |             Linearized
      qtsmok |      Coef.   Std. Err.      t    P>|t|     [95% Conf. Interval]
-------------+----------------------------------------------------------------
        male |  -.1715913   .1273081    -1.35   0.178    -.4211643    .0779817
         age |  -.0326805   .0053098    -6.15   0.000    -.0430898   -.0222713
     married |   .0156776   .1427494     0.11   0.913    -.2641663    .2955215
       white |  -.5607068   .1443603    -3.88   0.000    -.8437088   -.2777048
   mdrt_educ |  -.0291425   .1441877    -0.20   0.840    -.3118061    .2535212
   high_educ |   .5113156   .1800797     2.84   0.005     .1582899    .8643414
   incm_mdrt |  -.0339146   .1557743    -0.22   0.828    -.3392925    .2714632
   incm_high |   .1405313   .1766122     0.80   0.426    -.2056968    .4867595
      canada |   1.802811   .2552666     7.06   0.000      1.30239    2.303233
     rPSPPPi |  -.0083975    .000842    -9.97   0.000    -.0100481   -.0067468
       wave2 |   2.111112   .1326945    15.91   0.000     1.850979    2.371244
       wave3 |   2.411039   .1389374    17.35   0.000     2.138668     2.68341
------------------------------------------------------------------------------
....................output ends here..............

The rPSPPPi is our price variable. We have more price variables but
logit results with them are similar to what reported here.

Thank you very much!

Lili

On 10/18/07, Steichen, Thomas J. <SteichT@rjrt.com> wrote:
> Why do you consider this an indication of something wrong?
>
> Having zero completely determined successes e(N_cds) and failures
> e(N_cdf) is what you prefer.
>
> Is your overall # of  records e(N) wrong?
>
> Show us some sample commands and output so we can see what you are doing.
>
>
> -----Original Message-----
>
> I checked the data just now. After running logit model with our
> dependent variable, the stored results show:
>
> e(N) = 5463
> e(N_cds) = 0
> e(N_cdf) = 0
>
> So seems there is something wrong in the data setup. Could anyone
> please give me some help?
>
>
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