multidimensional scaling with rank data

[sr-3]

Hello Spss newsgroup,

I have a problem with the multidimensional scaling option in spss
(version12).
My data: 222 individuals who ranked 6 objects corresponding to their
personal preferences.

I want to produce a figure that shows the individuals and the objects
in a 2 dimensional space so that closeness of an individual to an
object means that the person likes the object more than other objects
that are in greater distance to the individual point.
Besides I wish to produce iso preference contours within the figure
so that (for example) two objects that are close to the same iso
preference contour are given almost the same ranks by an individual
close to that iso preference contour.

The technique to get this figure is unfolding according to the ideal
point model. I used the ASCAL algorithm (I think PROXSCAL is NOT
suitable, correct?) of SPSS but I got an error: too few cases...??
Syntax:

ALSCAL
  VARIABLES= object1 object2 object3 object4 object5 object6
  /SHAPE=RECTANGULAR /INPUT ROWS(222)
  /LEVEL=ORDINAL
  /CONDITION=ROW
   /MODEL=EUCLID
  /CRITERIA=CONVERGE(.001) STRESSMIN(.005) ITER(30) CUTOFF(0) DIMENS(2,2)
  /PLOT=DEFAULT .


Does anybody know how to solve the problem?
Or is it impossible to do unfolding of ranking data with SPSS?

I found shareware in the internet that seemed to be suitable for
unfolding (permap) but I won't start with another software unless i'm
shure that it's impossible to solve the problem with SPSS.

Besides I would like to know whether it's possible to do unfolding
(with SPSS) with aggregated data because another aim of my data
analysis is to compare groups of individuals and their preferences.

Thanks for help!

Susan

--


Der GMX SmartSurfer hilft bis zu 70% Ihrer Onlinekosten zu sparen!
Ideal für Modem und ISDN: http://www.gmx.net/de/go/smartsurfer

[Busing, Frank]

Dear Susan and list.

Ranked data can be analyzed with SPSS, with the procedure PREFSCAL.
It can handle multiple sources of individuals too.
Please check out this option,
or send me an e-mail,
so I can give more directions.
The program found: prefmap, can only do external unfolding.

Kind regards, Frank.


-----------------------------------------------
 Frank M.T.A. Busing
 Psychometrics and Research Methodology
 Leiden University
 P.O.Box 9555, 2300 RB Leiden, The Netherlands
-----------------------------------------------

-----Original Message-----
From: SPSSX(r) Discussion [mailto:[hidden email]] On Behalf Of sr
Sent: 18 August 2006 18:39
To: [hidden email]
Subject: multidimensional scaling with rank data

Hello Spss newsgroup,

I have a problem with the multidimensional scaling option in spss (version12). My data: 222 individuals who ranked 6 objects corresponding to their personal preferences.

I want to produce a figure that shows the individuals and the objects in a 2 dimensional space so that closeness of an individual to an object means that the person likes the object more than other objects that are in greater distance to the individual point. Besides I wish to produce iso preference contours within the figure so that (for example) two objects that are close to the same iso preference contour are given almost the same ranks by an individual close to that iso preference contour.

The technique to get this figure is unfolding according to the ideal point model. I used the ASCAL algorithm (I think PROXSCAL is NOT suitable, correct?) of SPSS but I got an error: too few cases...??
Syntax:

ALSCAL
  VARIABLES= object1 object2 object3 object4 object5 object6
  /SHAPE=RECTANGULAR /INPUT ROWS(222)
  /LEVEL=ORDINAL
  /CONDITION=ROW
   /MODEL=EUCLID
  /CRITERIA=CONVERGE(.001) STRESSMIN(.005) ITER(30) CUTOFF(0) DIMENS(2,2)
  /PLOT=DEFAULT .

Does anybody know how to solve the problem?
Or is it impossible to do unfolding of ranking data with SPSS?

I found shareware in the internet that seemed to be suitable for unfolding (permap) but I won't start with another software unless i'm shure that it's impossible to solve the problem with SPSS.

Besides I would like to know whether it's possible to do unfolding (with SPSS) with aggregated data because another aim of my data analysis is to compare groups of individuals and their preferences.

Thanks for help!

Susan

--


Der GMX SmartSurfer hilft bis zu 70% Ihrer Onlinekosten zu sparen! Ideal für Modem und ISDN: http://www.gmx.net/de/go/smartsurfer



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