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Re: st: Data Management question


From   Nick Cox <njcoxstata@gmail.com>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   Re: st: Data Management question
Date   Tue, 25 Jun 2013 18:02:58 +0100

You said

"I could do this the long way with repeated gen and replace commands".

Actually that sounds a nightmare without some small tricks. Here are mine:

egen ABCDE = concat(A B C D E)

For consecutive 1s, the trick is only that somewhere in the string
concatenation we will find "111" or "11".

gen X = strpos(ABCDE, "111") > 0
gen Y = strpos(ABCDE, "11") > 0

Your third definition splits into two

For one non-consecutive 1, the condition "non-consecutive" is superfluous.

For two non-consecutive 1s, there are in total two 1s and they must
not  be consecutive. The variable -Y- already codes two consecutive
1s.

Either way, try

gen Z = inlist(A + B + C + D + E, 1, 2) & !Y

Nick
njcoxstata@gmail.com

On 25 June 2013 17:46, Hitesh Chandwani <hchandwani.stata@gmail.com> wrote:

> I have a data management issue. I need to generate a couple of
> indicator variables from variables that already exist in the dataset.
>
> Let's call the required indicator vars X, Y, and Z with values of 1 or
> 0. Whether the value of these vars is 1 or 0 depends on the value of 5
> other indicator variables (A, B, C, D, E). A-E are chronologically
> ordered (i.e., A indicates an event that happened before B, which
> happened before C, and so on).
>
> For each observation:
> X = 1 if at least 3 "consecutive" vars from A-E are equal to 1.
> Y = 1 if at least 2 "consecutive" vars from A-E are equal to 1.
> Z = 1 if only 1 or 2 "non-consecutive" vars from A-E are equal to 1.
>
> I could do this the long way with repeated gen and replace commands
> but I'm sure there's a better way to do it (only I don't know how).
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