Re: st: Using tsset on panel data that are differentiated by two id variables

[Nick Cox <njcoxstata@gmail.com>]

There is a general discussion at

SJ-7-4  dm0034  . . . Stata tip 52: Generating composite categorical variables
        . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  N. J. Cox
        Q4/07   SJ 7(4):582--583                                 (no commands)
        tip on how to generate categorical variables using
        tostring and egen, group()

.pdf at http://www.stata-journal.com/sjpdf.html?articlenum=dm0034

But your last remark rules that out.

So why is #2 not working? Because by default your new variable is
-float-. Make it -double- and read Bill Gould's blogs on precision
every day until memorised!

Nick

On Wed, Nov 7, 2012 at 8:35 PM, Ben Hoen <bhoen@lbl.gov> wrote:

> I have run into problems setting a set of data as panel because my panels
> are differentiated by two numeric ids (muni_code %8.0g & parcel_id %12.0g)
> both with values 1 to 999,999. For example I might have the following cases.
>
> muni_code         parcel_id
> 22000             59
> 22000             60
> 22000             600
> 22000             601
> 27600             32199
>
> Because I cannot use a var list (at least I don’t think I can) as panel
> variables in tsset, I would like to combine the variables while also
> preserving the ids so that they are both usable as a merge variable and are
> descriptive in their values.  So, for example, I tried:
>
> 1) Using tostring to make a variable (muni_parcel_text) that looked like
> this “22000.59” “22000.60” “22000.600”, “22000.601”  and “22000.5983” and so
> on but the tsset wont accommodate a string variable
>
> 2) I then tried using the following formula .g muniparcel=(muni_id*100000) +
> parcel_id, which I then formatted as %12.0f (.format muniparcel %12.0f) but
> strangely got weird values such as 22000060, 2200000000, 2200000000,
> 22000000512 and 2200000512, and 2760032256, respectively.  I would have
> expected to get 22000000059, 22000000060, 22000000600, 22000000601, and
> 27600032199, respectively.
>
> Any idea how to how best to use these two variables as a panel variable,
> while preserving their values in some way?   Seperately, any idea why option
> #2 is not resulting in the expected answer?
>
>
> FYI, for one file, I could just use .egen muniparcel=group(muni_code
> parcel_id) and use muniparcel as the panel variable, but then I would not be
> able to merge with another dataset because the group numbers would not
> necessarily align.

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