User Guide

461
Two S t e p C l u s t e
rAnalysis
variable names in the main dialog box in the same order in which they were specified
in the prior analysis. The XML file remains unaltered, unless you specifically
write the ne
w model information to the same filename. For more information, see
“TwoStep Cluster Analysis Output” on p. 463.
If a cluster model update is specified, the options pertaining to generation of the
CF tree that
were specified for the original model are used. More specifically, the
distance measure, noise handling, memory allocation, or CF tree tuning criteria
settings for the saved model are used, and any settings for these options in the dialog
boxes are i
gnored.
Note: When performing a cluster model update, the procedure assumes that none
of the selected cases in the working data file were used to create the original cluster
model. Th
e procedure also assumes that the cases used in the model update come
from the same population as the cases used to create the original model; that is, the
means and variances of continuous variables and levels of categorical variables are
assumed t
o be the same across both sets of cases. If your “new” and “old” sets of
cases come from heterogeneous populations, you should run the TwoStep Cluster
Analysis procedure on the combined sets of cases for the best results.