Hi, I am using correspondence analysis to examine degrees
of homogamy/social distance in society using the occupations of husbands
and wives as markers of social position. I have done this over five
historical points using New Zealand census data (1981-2001). I'm using the
dimension scores (1 and 2) of the CA process to achieve a ranked
scale of homogamy/social interaction . It is expected that the order of the
ranking will be similar to that of the ranking of occupations in the issco
model . This indeed is the case with three of the time periods. At two points in
time however this ranking is inverted. Has anyone got tips on how to
explain this/switch this around? I believe that the 'best fit model' in
correspondence analysis can be a little nebulous. Greenacre talks
about 'rotating the axis.' Will this work and how might I do this in
SAS?

Any help will be useful.

Cheers, Stephen

Hi,

I am hoping someone here can help me with a “how to” question
on running McIntyre and Blashfield’s (1980) nearest-centroid evaluation
procedure to validate the stability of my cluster analysis solution. I am a
newbie to cluster analysis, so this is my first time running this procedure.

I have a sample of about 900 observations and have
randomly split the sample in two (Sample A and Sample B). I conducted
hierarchical cluster analysis and then calculated the centroid vectors for a
3-cluster solution on each of these two subsamples (i.e., steps 1 through 4 of
McIntrye and Blashfield’s evaluation technique).

Step 5 of McIntrye and Blashfield’s technique is to calculate
“the squared Euclidean distance for each of Sample B’s objects from each of the
centroids of Sample A,” and Step 6 is to assign “each object in Sample B
to the closest centroid vector.” At this point, I am not sure what buttons to
press in SPSS to complete the analysis. One possibility I tried is to use
K-means cluster analysis to achieve these two steps, but K-means uses simple
Euclidean distance (not squared Euclidean distance as recommended by McIntyre
and Blashfield) to assign the observations to clusters. Is this okay? (someone
told me it was, but I just want to double-check). I would greatly
appreciate any guidance on what buttons to press in SPSS/appropriate syntax to
complete steps 5 and 6 of this analysis.

Thank you.

Liza Rovniak

Liza S. Rovniak, PhD, MPH

Adjunct Assistant Professor

Center for Behavioral Epidemiology & Community
Health

Graduate School of Public Health, San Diego State
University

San Diego, CA 92123

Phone: 858-505-4770, ext. 152; Fax:
858-505-8614

Email: [log in to unmask]