To be sure, are the "random effects" and "fixed effects" of the answer the -RE and -FE options of xt-
series commands?
Also, as xtgee does not have such option, then can I use time invariant variables anyway?
> ---- Original Message ----
> From : Christer Thrane [[email protected]]
> To : [email protected]
> Date : 2006�� 5�� 28��(��) 01:38:38
> Subject : st: Re: Time invariant variables and panel data
>
>
>Hi,
>
>If you estimate random effects models, you can have both time-varying and
>time-invariant variables on the right hand side.
>
>If you estimate fixed effects models, you must have time-varying on the
>right hand side. But fixed effects also handles interactions between
>time-varying and time-invariant right hand side variables. (Then the
>interaction is no longer time-invariant.)
>
>Take a look at Woldridge's Basic Econometrics. A modern introduction--it's
>on Stata website.
>
>HTH
>
>Christer
>************************************************
>Professor Christer Thrane
>Department of Social Science
>Lillehammer University College
>2626 Lillehammer, Norway
>+ 47 61 28 81 70 (fax)
>+ 47 61 28 82 47 (phone, work)
>+ 47 61 25 53 04 (phone, home)
>E-mail, work: [email protected]
>E-mail, home: [email protected]
>************************************************
>
>
>
>----- Original Message -----
>From: "Rho YH"
>To:
>Sent: Saturday, May 27, 2006 4:48 PM
>Subject: st: Time invariant variables and panel data
>
>
>>I have incidentally found that panel data models (as far as I found the
>>Statalist, xtreg with -FE option)
>> cannot have time invariant variables and will be automatically omitted
>> when included.
>> In a general sense, then all xt- models (including xtgee) cannot have time
>> invariant variables?
>> Or in what instance does this fact come in effect?
>> Second, then does this mean that I cannot use time invariant variables
>> (like sex (M/F)) even
>> when these variables may be important?
>> I have two books about panel data (Twisk, and Sophia Rabe-Hesketh) but did
>> not find this fact.
>> Is it written in these books?
>>
>
>
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