Re: st: Question on Logit/Probit

["Jeremy Miles" <jeremy.miles@gmail.com>]

I think you want to use a beta regression.  I don't know if it exists
(I've never tried to find it in Stata).  It's similar to the
logit/probit approach, in that it transforms the data, and then
estimates the parameters using ML.

There was a paper by Smithson in Psychological Methods on this
recently - the abstract is here:
http://content.apa.org/journals/met/11/1/54

Jeremy



On 25/03/07, David Cobey <dcobey@gmail.com> wrote:
> I'm trying to estimate the percentage of an area under high yield variety
> crops as time changes. I hoping to estimate a basic S shaped technology
> diffusion model.  Can I use logit and probit for a continuous dependant
> variable ranging from 0-1 or does logit/probit only work for discrete
> variables?
> If logit and probit won't work, how should I estimate this S shaped model?
>
> Example of data -
>
> Year    Percentage
> 1965        0
> 1966      .1
> 1967      .3
> 1968      .6
> 1969      .8
> 1970      .9
> 1971      1
>
> Thanks!
> David
>
> -----Original Message-----
> From: David Cobey [mailto:dcobey@gmail.com]
> Sent: Saturday, March 24, 2007 6:15 PM
> To: 'statalist@hsphsun2.harvard.edu'
> Subject: RE: Data management
>
> Other people may have better ideas but here is what I would do.
>
> I would create a temporary variable for each id to hold the changes and then
> copy them over all at once.
>
> Ex:
>
> egen id= group(code)
> gen temporary_id = .
>
> replace temporary_id=3 if id==1;
> replace temporary_id=5 if id==2;
> replace temporary_id=8 if id==3;
>
> then:
>
> id = temporary_id
> drop temporary_id
>
> Hope this helps,
> David
>
> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu
> [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Roy,Suryadipta
> Sent: Saturday, March 24, 2007 5:59 PM
> To: statalist@hsphsun2.harvard.edu
> Subject: st: Data management
>
> Hi,
>
> I have a panel data of (say) 100 countries for 10 years. I
> am trying to attach identification numbers for these
> countries based on another dataset for merging purposes
> later on. So, I started with
>
> a. egen id= group(code), where "code" is the code numbers
> of these countries, e.g. ABW, AFG etc.
>
> b. Then I am trying to replace these id-s with
> replace id=3 if id==1;
> replace id=5 if id==2;
> replace id=8 if id==3;
>
> But the 3rd line of the command is replacing the first set
> of id-s also. I would greatly appreciate if someone can
> suggest how to take care of this.
>
> Thanks,
> Suryadipta.
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--
Jeremy Miles
Learning statistics blog: www.jeremymiles.co.uk/learningstats
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