st: egen or other methods to calculate consecutive row totals?

[Alexandra de Montrichard <ademontr@attbi.com>]

I am somewhat new to stata and I need some help with a problem I can't 
seem to resolve.

I am working with a database of students for whom I have quarterly 
grades for 5 years (1995-2000). I also have the start & completion date 
for a class that all students took a one point during those five year. I 
need to figure out how many quarters of grades I have for each student 
before & after they took this class & how many are consecutive quarters 
of grades. I've created a 0-1 variable for each quarter (0 if the 
student did not get any grades that quarter, 1 if they received a 
grade), converted the class start & exit date into quarter format & used 
egen to count of the number of quarters in which each student received 
grades
. egen byte gradenbr = neqany (grade951-grade004), v (1)
However, I now need to figure out a way of counting the number of 
quarters with grades both before & after the class as well as a way to 
know how many consecutive quarters with grade I have after completion of 
the class. I though I could use egen combined with if to create a 
gnbrpost variable of the number of quarters with grades after completion 
of the class:
. egen byte gnbrpost = neqany (grade951-grade004) if (exitdq== 
q(1995q1)), v (1)
. egen byte gnbrpost = neqany (grade952-grade004) if (exitdq== 
q(1995q2)), v (1)
. egen byte gnbrpost = neqany (grade953-grade004) if (exitdq== 
q(1995q3)), v (1)  etc.....

but I can't figure out how to replace the gnbrpost variable each time I 
run a new egen calculation plus I'm sure there must be a better way of 
doing this, which would also allow me to know how many consecutive 
quarters of grades I have.

Thanks!
Alexandra de Montrichard


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