# Re: st: Computing GDP growth using a log-linear regression

 From "Austin Nichols" To statalist@hsphsun2.harvard.edu Subject Re: st: Computing GDP growth using a log-linear regression Date Mon, 21 Jul 2008 10:51:20 -0400

```D Harwood <bus4dpah@leeds.ac.uk>:

Take the double quotes off =="`var'" is the short answer--you can't
compare a number to a quoted string.
But are you sure you want the avg change computed over all years (i.e.
the trend, not the annual GDP growth rates)?
And there is no need to generate yearcounter that I can see...

On Mon, Jul 21, 2008 at 10:41 AM, D Harwood <bus4dpah@leeds.ac.uk> wrote:
> Dear All,
>
> I was wondering if anyone knew how to compute GDP growth rates by country. I
> have panel data arranged as follows:
>
> Country             Year            GDP (\$ 2000)
> Benin               1997            1947193088
> Benin               1998            2035610240
> Benin               1999            2131227520
> Benin               2000            2254838784
> Benin               2001            2367580672
> Benin               2002            2474121728
> Benin               2003            2570612480
> Benin               2004            2650301440
> Benin               2005            2727160320
> .
> .
> .
>
> And so on for a number of countries. Arranged by country code and by year.
>
> I found an example in the archives of how to calculate the growth rates
> (http://www.stata.com/statalist/archive/2006-05/msg00529.html) and yet when
> I try to do the same I get an error message 'Type mismatch', no matter which
> variable type I enter. I typed the following into the command box and came
> out with the output shown.
>
> . egen minyearbycountry = min(year), by(code)
> r; t=0.00 15:30:23
>
> . gen yearcounter = year-minyearbycountry
> r; t=0.01 15:30:31
>
> . gen g = .
> (288 missing values generated)
> r; t=0.00 15:30:39
>
> . levelsof code
> 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
> 29 30 31 32
> r; t=0.01 15:30:48
>
> . foreach var in `r(levels)' {
>  2. reg lnGDP yearcounter if code =="`var'"
>  3. replace g = _b[yearcounter] if code =="`var'"
>  4. }
> type mismatch
> r(109); t=26.93 15:31:23
>
> I would be grateful if anyone could point out where I have gone wrong?
>
> Regards,
>
> Dave
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```