--- In [email protected], "Scott Merryman" <smerryman@k...>
wrote:
> ----- Original Message -----
> From: "West Addison" <wastata@y...>
> To: <statalist@h...>
> Sent: Friday, October 10, 2003 6:31 PM
> Subject: st: Invalid syntax in -xtdes- command
>
>
> > I have a panel data set and attempted to run the xtdes
> > command on it in Stata version 7 for Windows. The
> > command started to run okay and produced the first few
> > lines of output but then failed with the error message
> > "invalid syntax r(198);". My syntax looks fine as far
> > as I can tell from the manual--I am just typing
> > "xtdes" with no options--by I am new to this command
> > and may be missing something. Is there a bug in
> > xtdes? Here is what my log looks like:
> >
> > . use E:\Projects\HAP\DataSets\analysis.dta
> >
> > . tsset id_number time_from_intake
> > panel variable: id_number, 394 to 1412
> > time variable: time_from_intake, -24 to 12,
> > but with gaps
> >
> > . xtdes
> >
> > id_number: 394, 399, ..., 1412
> > n = 288
> > time_from_intake: -24, -23, ..., 12
> > T = 37
> > Delta(time_from_intake) = 1; (12--24)+1 =
> > 37
> > (id_number*time_from_intake uniquely
> > identifies each observation)
> >
> > Distribution of T_i: min 5% 25% 50%
> > 75% 95% max
> > 1 1 1 3
> > 5 14 29
> > invalid syntax
> > r(198);
> >
> > .
>
> The problem is that you have negative time values. If you -set
trace on- and
> then run -xtdes- you will see that it chokes when tries to create a
new variable
> named _T`time value', but _T-24 is not a valid name.
>
> From the trace:
>
> - gen int _T`i' = 1 if `tvar'==`i'
> = gen int _T-24 = 1 if t==-24
> invalid syntax
>
> If you create a new time variable, such as
>
> gen time2 = time_ + 24
>
> xtdes should work fine.
>
> Hope this helps,
> Scott
>
Thanks, Scott. You seem to a have pinpointed the problem with
xtdes. I would say this is a bug, because the manual, in the entry
for xt, states that negative values of the time variable are allowed:
"[The time variable] must be a single, numeric variable, although
whether it takes on the values 1, 2, 3 or 1, 7, 9, or even -2, sqrt
(2), pi is irrelevant."
Thanks again for your help.
West
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