Date:         Sun, 1 Apr 2012 14:55:57 -0400
Reply-To:     "Maguin, Eugene" <emaguin@buffalo.edu>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         "Maguin, Eugene" <emaguin@buffalo.edu>
Subject:      Re: Setting bits in SPSS variable
In-Reply-To:  <043c01cd1036$009fbf40$01df3dc0$@gmail.com>
Content-Type: multipart/alternative;

Mike,
There a couple of different ways of doing something like what you want. Assuming VarA-VarC has value 0,1.
Using strings.
String comb(a3).
Compute comb=concat(string(vara,f1.0), string(varb,f1.0), string(varc,f1.0)).

Using numeric
Compute comb=100*vara+10*varb+varc.

Gene Maguin

From: SPSSX(r) Discussion [mailto:SPSSX-L@LISTSERV.UGA.EDU] On Behalf Of Mike Pritchard
Sent: Sunday, April 01, 2012 2:34 PM
To: SPSSX-L@LISTSERV.UGA.EDU
Subject: Setting bits in SPSS variable

Is there an easy way to set bits in a an SPSS variable?  I'm trying to create a variable based on the combinations of other (dichotomous) variables.  The way that seems logically easy to me is to set a bit for each of the variables, and then the output variable will automatically represent the correct combination.  Thus (pseudo code)

IF (VarA) COMPUTE Comb = Comb AND 1.
IF (VarB) COMPUTE Comb = Comb AND 2.
IF (VarC) COMPUTE Comb = Comb AND 4.

Etc.

But I can't figure out how to do this.  Instead, I'm using all the combinations with individual IF statements which works for a small number, but isn't very scalable and is easy to make mistakes.

COMPUTE Comb=$SYSMIS.
IF ((VarA=1) AND (VarB=1) AND (VarC=1)) Comb=7.
IF ((VarA=1) AND (VarB=1) AND (VarC=0)) Comb=6.
IF ((VarA=1) AND (VarB=0) AND (VarC=1)) Comb=5.
IF ((VarA=1) AND (VarB=0) AND (VarC=0)) Comb=4.
IF ((VarA=0) AND (VarB=1) AND (VarC=1)) Comb=3.
IF ((VarA=0) AND (VarB=1) AND (VarC=0)) Comb=2.
IF ((VarA=0) AND (VarB=0) AND (VarC=1)) Comb=1.
IF ((VarA=0) AND (VarB=0) AND (VarC=0)) Comb=0.
EXECUTE .

As usual with my questions, this feels like something that should be obvious.

Thanks in advance.
Mike

_________________________________________________________________________
Mike Pritchard | mikep@5circles.com<mailto:mikep@5circles.com> | 5 Circles Research<http://www.5circles.com/> | 425-444-3410 (c) | 425-968-3883 (o)
Research to help companies build products that people buy

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