Not so. Each person can have one or more
spells on each -Brand-. Your code lumps
them all together.
Nick
n.j.cox@durham.ac.uk
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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