Re: st: Elapsed Time Paneldata

[Nick Cox <njcoxstata@gmail.com>]

My code is just an application of -by:-.

When the data are explicitly -sort-ed in the usual panel order, first
by identifier and then by -date-, then you can always refer to the
first -date- of each panel as -date[1]-.

I wrote a tutorial

SJ-2-1  pr0004  . . . . . . . . . . Speaking Stata:  How to move step by: step
        . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  N. J. Cox
        Q1/02   SJ 2(1):86--102                                  (no commands)
        explains the use of the by varlist : construct to tackle
        a variety of problems with group structure, ranging from
        simple calculations for each of several groups to more
        advanced manipulations that use the built-in _n and _N

a .pdf of which is accessible at

http://www.stata-journal.com/sjpdf.html?articlenum=pr0004

Despite its title, this FAQ is also pertinent

FAQ     . . . . . . . . . . . . . . . . . . . . . . . Generating the last date
        . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  N. J. Cox
        4/05    How can I generate a variable containing the last of
                several dates?
http://www.stata.com/support/faqs/data-management/generating-last-date/

Knowing that -by:- is the answer depends on knowing that command well, but

. search date, faq

would have pointed to the FAQ and in turn to a -by:- approach.

Nick

On Sun, Jan 20, 2013 at 5:41 PM, Steven Archambault
<archstevej@gmail.com> wrote:
> Thanks so much. I spent hours trying to figure this out. I need to
> improve my programming skills. If you can recommend a Stata training
> session, or other resources, please do.
>
>
> On Sun, Jan 20, 2013 at 4:45 AM, Nick Cox <njcoxstata@gmail.com> wrote:
>> bysort newid (date) : gen elapsed = date - date[1]
> *
> *   For searches and help try:
> *   http://www.stata.com/help.cgi?search
> *   http://www.stata.com/support/faqs/resources/statalist-faq/
> *   http://www.ats.ucla.edu/stat/stata/
*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/faqs/resources/statalist-faq/
*   http://www.ats.ucla.edu/stat/stata/