Re: st: replacement task

[Richard Williams <Richard.A.Williams.5@nd.edu>]

At 03:54 PM 1/21/2004 -0600, Dimitriy V. Masterov wrote:
> I could not find a command that performs this simple task. I was hoping if
> someone might have some advice. I have a variable named emp that looks
> like this
>
> emp     Freq.
> 0       93,404
> 1       55,537
> 2       36,556
>
> I want to replace emp=2 at random with 0 or 1 depending on the relative
> number of 1s and 0s in the sample. My outcome should look like this
>
> emp     Freq.
> 0       116,329
> 1       69,168
Incidentally, if you happen to have Nick Cox's -egenmore- installed (type 
-findit egenmore-) this will also work (the rndsub fnc as shown below 
randomly assigns cases to 2 groups, with 62.71% going to group 1 and the 
rest to group 2; this assignment only occurs where emp = 2).

. egen x = rndsub() if emp==2, ng(2) p(62.712081)
(148941 missing values generated)

. replace emp = x-1 if emp ==2
(36556 real changes made)

. tab emp

        emp |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |    116,329       62.71       62.71
          1 |     69,168       37.29      100.00
------------+-----------------------------------
      Total |    185,497      100.00

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