Dear All,


I'm pretty new to Stata, and am having difficulty in creating for loops for the following dataset.

I have several types of variables(Y,X...) which are in fact observations taken from several years(2-12). e.g. aY2-aY13, aX2-aX12.... and so on and so forth.
I want to generate a new set of variables, which are the cumulative sums of each of the prior observations. e.g. Cumul aY5 =
aY2 + aY3 + aY4 + aY5.

I am guessing that the solution is probably nesting a for loop inside another ( one for the number at the end, and the other for the variable types), but I'm not sure how to go about it.


Hypothetical observation and output below(with 2 observations, 2 variable types, 3 years):

aY1 aY2 aY3 aX1 aX2 aX3 Cumul aY2 Cumul aY3 Cumul aX2 Cumul aX3
1 2 3 4 5 6 3 6 9 15
3 4 2 7 1 3 7 9 8 11

Thanks so much!