Re: st: How to skip logit when there is no variation in the dependentvariable

[Thomas de Hoop <T.deHoop@maw.ru.nl>]

Thomas de Hoop wrote:
> Dear Statalist users,
>
> I have created dummy variables for 214 countries. For each of these 
> countries I want to estimate several logit models to estimate chances 
> of certain situations to occur,  and create chance variables from the 
> prediction of these models. I estimate these chances using data from 
> the past. I have data of these situation For this I created loops with 
> the foreach and forvalue commands from stata. The problem is that in 
> some countries a certain situation never occurred. For these 
> situations there are only 0 value observations. Of course logistic 
> regression is not possible in these kind of situations. For this 
> reason I would like to skip these equations in the loop.
> For this reason I counted the number of times a situation did occur in 
> the past and created a variable.
>
> I tried to skip the equation as follows:
>
> forval i=1/214 {
> logit drought`i' variable1 variable 2 etc. if  droughtcount`i'>0
> }
>
> i= the country number
> variable1 variable2 etc are the explanatory variables.
>
> drought`i'=the situation in a certain country
> droughtcount`i'=the number of times a situation did occur in the past.
>
> For country 3 this results in the following error:
> no observations
> r(2000);
I add some more information that might be useful. Country 3 is a country 
where the situation never occurred.

> How can I prevent this error?
>
> Best regards,
>
> Thomas de Hoop
>
>
>
>
>
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