Purnima Chawla (pchawla@ETS.ORG) wrote: : Hello, everyone. : I'm trying to do a cluster analysis based on how people have responded to : a survey. Some of the questions in the survey required a Y/N response : and thus yield binomial data. Others required a Likert type response; : still others were designed like multiple choice questions but are graded : and can be interpreted as ordinal data.

: My question is this: how should the proximities be calculated if some of : the data are binomial and some are ordinal? Also, does SPSS do this?

How? carefully!

a) SPSS Proximities has a number of possibilities for scoring distances or proximities for binomial data. It is possible to use a subset of variables, and create a Distance-score from dichotomies; then use that as just one among another set of variables.

b) the default (without STANDARDIZE) means that a variable scored 0-100 would have 10 or 100 times the weight as a variable scored 1-10. Et cetera.

c) the choice of VARIABLES going into your distances is what the weighting will be computed over; if there are 10 trivial variables and one important one, the distances will be not depend much on the important one....

Rich Ulrich, biostatistician wpilib+@pitt.edu http://www.pitt.edu/~wpilib/index.html Univ. of Pittsburgh