Date:         Wed, 3 Apr 2002 22:30:42 +0100
Reply-To:     "R. Allan Reese" <R.A.Reese@gri.hull.ac.uk>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         "R. Allan Reese" <R.A.Reese@gri.hull.ac.uk>
Subject:      Re: Duplicate question
Comments: To: Hector Maletta <hmaletta@fibertel.com.ar>
In-Reply-To:  <3CAB6655.1EFA1FC1@fibertel.com.ar>
Content-Type: TEXT/PLAIN; charset=US-ASCII

Just to add a grace note to Hector's response, it is sensible to SORT thecases as a duplicate ID is possibly a mistyping so will be in the wrong
order.  I have just used such an idea to add jitter to make colocated
points visible on a scatterplot.  Only the "duplicate" points need be
moved:

sort cases by x y.
compute dup= (x eq lag(x)) and (y eq lag(y)).
compute jit= uniform(1)-0.5.
compute xj= x + dup*jit.
compute yj= y - dup*jit.

(BTW: I didn't paste this syntax, so apologies for any typos.)

R. Allan Reese                       Email: r.a.reese@gri.hull.ac.uk