Hi Martin,
thanks for your answer. I also had the problem of convergence when I tried to calculate models 2,3 and 4 with clogit. But model 1 works fine with my data.
An excerpt of my data looks as follows:
id IV DV1 DV2 |
|-------------------------|
1. | 1 0 0 0 |
2. | 1 0 0 0 |
3. | 1 0 0 0 |
4. | 1 0 0 0 |
5. | 1 1 0 0 |
|------------------------|
6. | 1 1 1 1 |
7. | 1 1 2 4 |
8. | 1 1 3 9 |
9. | 1 1 4 16 |
do clogit and logit come to the same results given that I seperate the data by id?
Or is there another way to model my probelm? It needn't be done with clogit. I think one big problem is that I separate my data by ids. And clogit also separates by id but doesn't give separate coefficients for each household.
-------- Original-Nachricht --------
> Datum: Tue, 10 Nov 2009 10:05:14 +0100
> Von: "Martin Weiss" <[email protected]>
> An: [email protected]
> Betreff: st: AW: clogit vs. logit
>
> <>
>
> When I try your lines
>
> *************
> keep if (id==1)
> clogit IV DV1 DV2, group(id)
> *************
>
> with the example in the help file for -clogit-, I just can`t get
> convergence...
>
> *************
> webuse lowbirth2, clear
> keep if pairid==1
> clogit low lwt smoke ptd ht ui i.race, group(pairid)
> *************
>
> Is this what you mean by "Unfortunately the clogit doesn't work for all
> models."?
>
>
> HTH
> Martin
>
>
> -----Ursprüngliche Nachricht-----
> Von: [email protected]
> [mailto:[email protected]] Im Auftrag von Regina
> Kemmler
> Gesendet: Dienstag, 10. November 2009 09:57
> An: [email protected]
> Betreff: st: clogit vs. logit
>
> Dear Statalist,
>
> I'd like to conduct a clogit analysis.
> I have a sample of several household for whom I'd like to calculate the
> beta
> coefficient for 4 different models and conduct the likelihood ratio test
> afterwards to test which model fits best. Unfortunately the clogit doesn't
> work for all models. But as the clogit and logit are supposed to give the
> same results given you have one group I did the following syntax.
>
> keep if (id==1)
> clogit IV DV1 DV2, group(id)
> gen b1_DV1=_b[DV1]
> gen b1_DV2=_b[DV2]
> gen lik1=e(ll)
> estimates store m1
>
> logit IV DV2
> gen b2_DV2=_b[DV2]
> gen kons2=_cons
> gen lik2=e(ll)
> estimates store m2
>
> logit IV DV1
> gen b3_DV=_b[DV]
> gen kons3=_cons
> gen lik3=e(ll)
> estimates store m3
>
> logit IV
> gen kons4=_cons
> gen lik4=e(ll)
> estimates store m4
>
> lrtest m1 (m2 m3 m4), stats
>
>
> Is it okay to mix up clogit and logit? Does it really give the same
> results?
> Why is it then not possible to calculate clogit on the latter 3 models?
> And:
> is it possible to conduct a likelihood ratio test if I mix up clogit and
> logit?
>
> Your help is much appreciated!
> Thanks a lot,
> Regina
>
>
>
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