> I have a question about "origin" and "enter" in stset using Stata 8.0. I am studing firms and their expansion into foreign markets. The firms are under observation from Jan 1 1991 to Dec 31, 2000. However, they are at risk of foreign expansion from their inception (when the firm was founded). I set up the data using the following command
> stset edate, id(unique) failure(enter) enter(time entdate) origin(time foundy2) exit(time .)
> Origin is the variable foundy2 which is an integer of the firm's founding date.
> Enter is a variable that records the date Jan 1, 1991 for every observation, because this is the date when the firms became under observation. I believe that this is the correct syntax. However for some reason when I check the _t0 and _t dates and when I use stdes, the firms are not calculated as being at risk from their founding date. In fact some of the firms were founded in 1848 so their time at risk should be much higher.
> Below is an example of the output from stedes. Note the earliest time at risk is 3403 and the max is 3653. Can anybody possibly help me with this. I would appreciate any help.
> failure _d: enter
> analysis time _t: (edate-origin)
> origin: time foundy2
> enter on or after: time entdate
> exit on or before: time .
> id: unique
>
> |-------------- per subject --------------|
> Category total mean min median max
> ------------------------------------------------------------------------------
> no. of subjects 2060
> no. of records 20671 10.03447 10 10 19
>
> (first) entry time 17297.77 1096 16071 52595
> (final) exit time 20950.77 4749 19724 56248
>
> subjects with gap 1
> time on gap if gap 250 250 250 250 250
> time at risk 7524930 3652.879 3403 3653 3653
>
> failures 71 .034466 0 0 9
> ------------------------------------------------------------------------------
>
>
> Thanks,
>
> Doug Thomas
>
> Anderson Schools of Management
> University of New Mexico
> MSC05 3090
> 1924 Las Lomas NE
> Albuquerque NM 87131-0001
> Phone: (505) 277-8892
> Fax: (505) 277-7108
> [email protected]
> http://www.unm.edu/~thomasd
>
>
> Thanks,
>
> Doug Thomas
>
> Anderson Schools of Management
> University of New Mexico
> MSC05 3090
> 1924 Las Lomas NE
> Albuquerque NM 87131-0001
> Phone: (505) 277-8892
> Fax: (505) 277-7108
> [email protected]
> http://www.unm.edu/~thomasd
>
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