I don't think you need any special commands
for this. 
I assume there is some other variable 
in this other than -raceid-. It looks 
like -finpos-. 
So 
bysort raceid (finpos) : gen nfinpos = (_n - 1)/(_N - 1) - 0.5 
as (_n - 1)/(_N - 1) will scale to [0,1]. 
Nick 
[email protected] 
[email protected]
 
> I am having trouble creating the following variable. I am 
> sure it is quite
> easy just escaping me for the past two days.
> 
> I have 80k horse races with a finishing position ranging from 
> 1-2 to 1-18.
> I have normalized the finishing position using the following:
> 
> sort raceid
> by raceid: get nfinpos=_N
> replace nfinpos=finpos/nfinpos
> 
> I would like to have the normalized finishing position 
> rescaled to -.5 to
> .5.
> 
> I can not find a command that lets me do this and allows by.
> 
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