Re: st: < and > operand in recode

[Dick Campbell <dcamp@uic.edu>]

I was in the midst of posting a response to this query when Nick Cox's very
complete answer arrived. Just two additional points. The full documentation 
for recode can be found in [D}, data management.
The key idea is that recode rules are evaluated left to right. Thus 
(1/5=1)(5/10=2) results in a value of 5 being recoded
to 1 even though "5" appears in both rules. Nick is certainly right; 
recoding continous variables can sometimes
result in unexpected outcomes. At the very least, it is a good idea to 
always use the -gen- option with recode rather than
overwrite the original variable and to immediately cross tabulate the 
original variable against the new.


At 07:54 AM 8/20/2006 Sunday, you wrote:

> hi all,
>
> Stata 8.2,
>
> i wanted to recode a variable, which consisted of continuous number, 
> something to the effect of:
>
> <=1 coded 1 (<= i.e. meaning less than or equal to)
> >1 to <=2 coded 2
> >2 to <= 5 coded 3
> >5 to <=10 coded 4
> >10 coded 5
>
> when i tried to use the equality operands (i.e. < or > in my recode 
> commands, it gives an error message 'unknown el <2 in rule') so after 
> consulting my manual on [R] recode, i managed by recoding:
>
> 0.0001/1 = 1
> 1.0001/2 = 2
> .
> .
> 10/1000 = 5
> etc
>
> being careful to make sure that the parameters included all the values.
>
> i would appreciate if someone could confirm that equality sign cannot be 
> used in recode. would appreciate it too if anyone can point out an 
> alternative/better way to accomplish the recode.
>
> many thanks,
> bw
>
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Richard T. Campbell
Professor
Division of Epidemiology and Biostatistics
School of Public Health &
  Institute for Health Research and Policy
University of Illinois at Chicago 

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