Dale Steele
>
> minus the value of response when resistnc is 0. Seems like
> I should use the
> "by" command, but I'm having a hard time creating working
> code. My efforts
> thus far ...
>
> by idnum: generate cresponse = response - (the value for
> response given
> resistnc = 0 for each idnum)
>
> . list idnum resistnc response
>
> idnum resistnc response
> 1. 401 0 .14
> 2. 401 2.5 2.42
> 3. 401 5 3.76
> 4. 401 10 4.74
> 5. 401 20 7.88
> 6. 401 30 8.52
> 7. 402 0 .4
> 8. 402 2.5 1.46
> 9. 402 5 1.58
> 10. 402 10 4.08
> 11. 402 20 6
> 12. 402 30 8.94
>
What reached me seemed to have lost at least one line,
but from this sample it seems that
bysort idnum (resistnc) : gen cresponse = response - response[1]
is sufficient to get what you what you want, as that puts
-resistnc- in order within -idnum-, and so -response[1]-
is then the response when -resistnc- is 0.
If -resistnc- were ever negative, you could do something
like this:
gen iszero = resistnc == 0
bysort idnum (iszero) : gen cresponse = response - response[_N]
Nick
[email protected]
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