Repeated ALSCAL - Multidimensional Scaling

[Steve Runfeldt]

I am conducting a quarterly tracking study.  Last quarter I produced some
MDS charts that were very enlightening for our client.  He said that he
would like to see them quarterly and compare the changes over time.

I now have four quarters of data and want to do this.  The problem is that
while the relationships between the variables seem fairly consistent over
time, the maps are rotated or flipped.  That is, in the first quarter, vars
a, b, and c, all appear clustered in quadrant 1 and d and e are clustered in
quadrant 2. In Q2, a, b, and c, are clustered in quadrant 3 and d and e are
in quadrant 1, as if map 1 was rotated 180 degrees.  In Q3 a, b and c are in
quadrant 3 and d and e are in quadrant 4, as if the map had been flipped.
The variables are pretty much in the same positions relative to one another.
It is just that they are moved relative to the map coordinates.

Does anyone know of a way to control for the location of, say, one key
variable and then place the others on the chart in relation to that?

Thanks,

Steve

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[Kooij, A.J. van der]

 
Dear List.
 
One way of controling the location of certain objects is to use fixed coordinates.
This is easily done with PROXSCAL, which allows for restrictions on the coordinates.
Another restriction would be to use individual differences over the quarters.
This is a model restriction, also possible with PROXSCAL.
 
The best of luck,
 
Frank Busing
Programmer of PROXSCAL
Leiden University
The Netherlands

________________________________

From: Kooij, A.J. van der
Sent: Thursday, January 17, 2008 3:46 AM
To: Busing, Frank
Subject: FW: Repeated ALSCAL - Multidimensional Scaling


 

________________________________

From: SPSSX(r) Discussion on behalf of Steve Runfeldt
Sent: Thu 17/01/2008 01:18
To: [hidden email]
Subject: Repeated ALSCAL - Multidimensional Scaling



I am conducting a quarterly tracking study.  Last quarter I produced some
MDS charts that were very enlightening for our client.  He said that he
would like to see them quarterly and compare the changes over time.

I now have four quarters of data and want to do this.  The problem is that
while the relationships between the variables seem fairly consistent over
time, the maps are rotated or flipped.  That is, in the first quarter, vars
a, b, and c, all appear clustered in quadrant 1 and d and e are clustered in
quadrant 2. In Q2, a, b, and c, are clustered in quadrant 3 and d and e are
in quadrant 1, as if map 1 was rotated 180 degrees.  In Q3 a, b and c are in
quadrant 3 and d and e are in quadrant 4, as if the map had been flipped.
The variables are pretty much in the same positions relative to one another.
It is just that they are moved relative to the map coordinates.

Does anyone know of a way to control for the location of, say, one key
variable and then place the others on the chart in relation to that?

Thanks,

Steve

=====================
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[hidden email] (not to SPSSX-L), with no body text except the
command. To leave the list, send the command
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