Hi Scott,
by sort pid (ob):gen cave = sum(calc)/ob
This is so obvious as to be painful. So why didn't I think of it?
1) Where/When did -sum()- become an acceptable argument to
-generate-!?!? I have only ever seen it in the context of -egen-.
Looking at the help for -generate-, there are no arguments that are
explicitly stated to be useable. It is only at the very bottom of the
examples that one sees an function -uniform- and then -sum- used with
gen. Are the others? I know that using many egen arguments with -gen-
will return errors (e.g. count).
2) Why does the ---bys pid (ob)-- do this correctly? I understand that
it is equivalet to --sort PID OB--, but why does it result in the
correct cumulative sum?
Another way of putting this is why doesnt -egen cave=sum(calc)/ob,
by(PID OB)- work if this does?
Sorry if this is a lot, I am just surprised about this.
Oh, and thanks. I did not get to try Dan Lawson's code.
Dan Egan
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
