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

[Nick Winter <nw53@cornell.edu>]

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.
>
> Thanks,
>
> Albet
>
>
>
>
>
> On 4/6/06, Nick Cox <n.j.cox@durham.ac.uk> wrote:
> > I think you are going to need to explain how "Duration"
> > is calculated. The numerical example is not
> > clear to me.
> >
> > Nick
> > n.j.cox@durham.ac.uk
> >
> > Albert Newton
> >
> > >        I get stuck in coding a during variable.  The data is like:
> > >
> > > hhid    weekshoppingday triptype        switch  switchtype
> > >   Duration
> > > 1871877 954     7       1       0       0       0
> > > 1871877 955     7       2       1       2       1
> > > 1871877 956     3       1       1       4       1
> > > 1871877 957     6       0       1       1       1
> > > 1871877 958     7       1       1       6       3
> > > 1871877 959     7       1       0       0       0
> > > 1871877 960     7       1       0       0       0
> > > 1871877 961     7       0       1       1       1
> > > 1871877 962     7       2       1       5       1
> > > 1871877 963     4       1       1       4       3
> > > 1871877 964     2       1       0       0       0
> > > 1871877 964     7       1       0       0       0
> > >
> > > I just wanto count how long the customer stay in the switched shopping
> > > type.  Could any one give some suggestion of how to constuct the
> > > variable "Duration"?
> > > The one above is make manually.
> >
> > *
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> >
>
> *
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________________________________________________________
Nicholas J. G. Winter                     607.255.8819 t
Assistant Professor                       607.255.4530 f
Department of Government              nw53@cornell.edu e
Cornell University        falcon.arts.cornell.edu/nw53 w
308 White Hall
Ithaca, NY 14853-4601 

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