Using PROC VARCLUS
Default options for PROC VARCLUS often provide satisfactory
results. If you want to change the final number of clusters,
use the MAXCLUSTERS=, MAXEIGEN=, or PROPORTION= option.
The MAXEIGEN= and PROPORTION= options usually produce
similar results but occasionally cause different clusters
to be
selected for splitting. The MAXEIGEN= option tends to choose
clusters with a large number of variables, while the PROPORTION=
option is more likely to select a cluster with a small number of
variables.
Execution time
PROC VARCLUS usually requires more computer time than principal
factor analysis, but it can be faster than some of the
iterative factoring methods. If you have more than 30
variables, you may want to reduce execution time by one or
more of the following methods:
- Specify the MINCLUSTERS= and MAXCLUSTERS= options
if you know how many clusters you want.
- Specify the HIERARCHY option.
- Specify the SEED statement if you have some
prior knowledge of what clusters to expect.
If computer time is not a limiting factor, you may want to
try one of the following methods to obtain a better solution:
- Specify the MAXSEARCH= option with principal
components and specify a value of 5 or 10.
- Try several factoring and rotation methods
with PROC FACTOR to use as input to PROC VARCLUS.
- Run PROC VARCLUS several times, specifying INITIAL=RANDOM.
Copyright © 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.
