RE: st: RE: How to construct a duration variable?

 From "Nick Cox" <[email protected]> To <[email protected]> Subject RE: st: RE: How to construct a duration variable? Date Thu, 6 Apr 2006 21:42:00 +0100

```Nick
[email protected]

> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of Alex Ogan
> Sent: 06 April 2006 21:39
> To: [email protected]
> Subject: RE: st: RE: How to construct a duration variable?
>
>
> Here's one in two lines:
>
> bysort hhid (period): gen tempvar = sum(switch)
> bysort hhid tempvar: gen myduration = _N
>
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of Nick Winter
> Sent: Thursday, April 06, 2006 4:14 PM
> To: [email protected]
> Subject: RE: st: RE: How to construct a duration variable?
>
> Good point.  Drat.
>
>
>
> At 04:05 PM 4/6/2006, you wrote:
> >Not so. Each person can have one or more
> >spells on each -Brand-. Your code lumps
> >them all together.
> >
> >Nick
> >[email protected]
> >
> >Nick Winter
> >
> > > I think
> > >
> > >    bysort hhid Brand: gen Duration=_N
> > >
> > > should do it.
> > >
> > > --Nick Winter
> > >
> > > At 01:42 PM 4/6/2006, you wrote:
> > > >Thank you, Nick.
> > > >
> > > >For example,  there are three brands in the market: A, B and C.
> One
> > > >consumer buy A at the first period.  At the second period, she
> > > >switches to B.  Since then, she keeps buying B for the next four
> > > >periods.  After that, she switches to C etc.
> > > >
> > > >Then the duration variable I want should be:
> > > >
> > > >hhid    Period   Brand    Switch  Duration
> > > >1         1         A           0           1
> > > >1         2         B           1           4
> > > >1         3         B           0           4
> > > >1         4         B           0           4
> > > >1         5         B           0           4
> > > >1         6         C           1           2
> > > >1         7         C           0           2
> > > >1         8         A           1           1
> > > >1         9         B           1           4
> > > >1        10         B           0           4
> > > >1        11         B           0           4
> > > >1        12         B           0           4
> > > >1        13         C           1           2
> > > >1        14         C           0           2
> > > >
> > > >I wish that it's clear this time.  I just not sure how
> to construct
> > > >the duration variable in Stata.
> >
> >
> >*
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> >*   http://www.stata.com/support/statalist/faq
> >*   http://www.ats.ucla.edu/stat/stata/
>
> ________________________________________________________
> Nicholas J. G. Winter                     607.255.8819 t
> Assistant Professor                       607.255.4530 f
> Department of Government              [email protected] e
> Cornell University        falcon.arts.cornell.edu/nw53 w
> 308 White Hall
> Ithaca, NY 14853-4601
>
>
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*
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```