Please, how mark the first or last case time variable. Thanks

[Augusto Sao]

* Example generated by -dataex-. To install: ssc install dataex
clear
input int id float(date_dx time)
1 16875 1
1     . 2
1     . 3
1     . 4
1     . 5
2 16967 1
2     . 2
2     . 3
2     . 4
2     . 5
3 13680 1
3     . 2
3     . 3
3     . 4
3     . 5
end
format %dM_d,_CY date_dx

------------------ copy up to and including the previous line ------------------

[Rich Goldstein]

your question is not completely clear to me, but here I add 2 variables: first and last:

. bys id (time): gen byte first=id!=id[_n-1]

. bys id (time): gen byte last=id!=id[_n+1]

. li, clean noo

    id          date_dx   time   first   last  
     1   March 15, 2006      1       1      0  
     1                .      2       0      0  
     1                .      3       0      0  
     1                .      4       0      0  
     1                .      5       0      1  
     2    June 15, 2006      1       1      0  
     2                .      2       0      0  
     2                .      3       0      0  
     2                .      4       0      0  
     2                .      5       0      1  
     3    June 15, 1997      1       1      0  
     3                .      2       0      0  
     3                .      3       0      0  
     3                .      4       0      0  
     3                .      5       0      1

you can of course label the new variables if you want; see

help label

[Augusto Sao]

Thank you !!!!. My problem is completely solved. It has helped me a lot !!!