Date:         Tue, 26 Mar 2002 16:41:49 +1100
Reply-To:     Sharon Morris <smorris@dbmcons.com.au>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         Sharon Morris <smorris@dbmcons.com.au>
Subject:      Identifying cases based on particular criteria
Content-Type: text/plain; charset="iso-8859-1"

HI,

I have what appears to be a simple problem to which I am having difficulty
coming up with a solution.

I have an SPSS file with around 1600 cases.  Each case represents a
household in a particular quarter of the year.  Some households have data
for only one quarter, others have data for two quarters, others three and
some have data for all four quarters.  A household with four quarters worth
of data is represented by four separate records, one for each quarter.

For each record, I have a variable which tells me which brand of a
particular product the household uses more - brand A or brand B.  This
variable may be consistent across quarters or not (households don't
necessarily stick with the same brand over time).  I need to categorise
households based on which brand (A or B) they predominantly buy.  I want to
select those households that have been consistent over time (however many
quarters I have data for them) and classify them as either A or B households
so I can then do a discriminant analysis on them to determine how households
who prefer A differ from households who prefer B.  How can I identify these
households?

The other thing I would like to do is to be able to select households that
have been mostly consistent over time (say, used product A more than product
B in at least 3 quarters if I have data for them for 4 quarters).  Once
again, I don't know how to identify and flag these households.

I am using SPSS 11, so I can easily restructure the data if necessary - I
suspect I will need to end up with only one case per household.

Any help would be appreciated!

Sharon Morris
Senior Project Manager
DBM Consultants Pty Ltd
5-7 Guest Street
Hawthorn VIC 3122
ph: 03 9819 1555 fax: 03 9819 9333

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