Eric Wruck's warnings about ties and missings
are very important.
If you use a string variable to keep track of which
variable or variables hold the maximum, you can also
note ties.
egen max = max(x1-x10)
gen which = ""
forval v = 1/10 {
replace which = which + " `v'" if x`v' == max
}
replace which = ltrim(which)
tab which
Also check out -rowranks- from SSC.
Nick
[email protected]
Eric G. Wruck
> Ok, here's a way of doing it: I made up a little example &
> wrote some code. This looks like it'll work:
>
> . l
>
> +--------------+
> | x1 x2 x3 |
> |--------------|
> 1. | 1 2 3 |
> 2. | 7 5 4 |
> 3. | 10 34 18 |
> 4. | 16 12 16 |
> +--------------+
>
> . gen maxX = 0
>
> .
> . egen max = rowmax(x*)
>
> .
> . forvalues i = 1(1)3 {
> 2. replace maxX = `i' if x`i' == max
> 3. }
> (2 real changes made)
> (1 real change made)
> (2 real changes made)
>
> .
> . l
>
> +---------------------------+
> | x1 x2 x3 maxX max |
> |---------------------------|
> 1. | 1 2 3 3 3 |
> 2. | 7 5 4 1 7 |
> 3. | 10 34 18 2 34 |
> 4. | 16 12 16 3 16 |
> +---------------------------+
>
> .
> .
> However, you need to watch out for at least two things: (1)
> ties & (2) missing values. The code I wrote takes the last
> maximum tie as the variable of interest -- that is, in
> observation 4, x3 is determined to hold the max even though
> x1 holds the same value. Missing values are effectively
> treated as positive infinity, so you may have to control for
> that separately -- this depends in part on what egen does
> with missing values.
Shawn
> >I have a series of variables, say x1-x10, and I would like
> to determine
> >the numeric suffix associated with the variable that has the maximum
> >value for each case. For example, maybe x9 has the max for
> case 1 and
> >x7 has the max for case 2, then I would like to end up with
> a variable,
> >say MaxX, that has a 9 and 7 for the first two cases respectively. I
> >think a data loop is the way to go, but I've tried working
> out a loop to
> >do this and it's not coming to me.
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