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st: RE: i-1 in forvalues loop
From
Nick Cox <[email protected]>
To
"'[email protected]'" <[email protected]>
Subject
st: RE: i-1 in forvalues loop
Date
Tue, 18 Oct 2011 15:11:30 +0100
I don't understand what you are trying to do. I comment only on obvious Stata problems.
`i-1' would only work if "i-1" were the name of a local macro, but it can't be such a name, as minus signs are not allowed in Stata names.
gen bal`i' = bal`=`i'-1' * 3166.467
would at first sight work as then Stata knows to evaluate the expression
`i' - 1
on the fly.
Your code largely consists of putting constants into variables, which is legal but not especially good style.
Note that
gen lotto=sum(studentsj3) //sum of target population
produces a _cumulative_ sum: only in the last observation will this be the actual sum, as your comment implies. Whether the comment or the code is what you want only you can say.
Nick
[email protected]
Viktor Emonds
I am trying to draw a sample with random start, fixed interval systematic sampling procedure in each explicit stratum. The data in each stratum are already sorted by all the implicit stratifiers with serpentine sorting for a variable of particular interest. Now I just need to do the actual sampling and tried to start by doing the following:
use ethnicframe31 //the specific explicit stratum
gen lotto=sum(studentsj3) //sum of target population
egen bal1= mean(3166.4667*runiform()) //random starting point
forvalues i=2/15 { //Draw ' lotto balls' by adding the fixed interval
gen bal`i'= bal`i-1'*3166.4667
}
gen winnaar=0 //Identify ' winning' schools
forvalues i=1/15{
replace winnaar=1 if inrange(bal`i',lotto[_n-1],lotto)
}
Apparently, the `i-1' in the first loop is not understood. What am I doing wrong here? Thanks in advance!
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