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
________________________________ From: Classification, clustering, and phylogeny estimation [mailto:[EMAIL PROTECTED] On Behalf Of Liza Rovniak Sent: Thursday, 4 September 2008 10:40 a.m. To: [email protected] Subject: cluster analysis validation technique 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: [EMAIL PROTECTED] ---------------------------------------------- CLASS-L list. Instructions: http://www.classification-society.org/csna/lists.html#class-l ---------------------------------------------- CLASS-L list. Instructions: http://www.classification-society.org/csna/lists.html#class-l
