Meryle Weinstein --
It's always advisable to frame your question in terms of data everyone
can use, e.g. by starting your example with -sysuse auto- and showing
the result you want. That said, one way (among many) to generate an
indicator for first year is:
egen minyr=min(year), by(bdsmaster)
gen fyr=(year==fyr)
On 5/17/07, Meryle Weinstein <[email protected]> wrote:
I've tried following the syntax in FAQ and archives but am having difficulty
with it. I have a dataset that has an idcode and a year for a number of
schools. I want to identify the first year that the idcode appears. I've
tried the following but still don't' get the first occurrence.
by bdsmaster (year), sort: gen noccur = sum(bdsmaster)
by bdsmaster: gen byte first = noccur == 1 & noccur[_n - 1] != noccur
gen byte first = sum(bdsmaster == 1) == 1 & sum(bdsmaster[_n - 1] == 1) ==
0
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