Hi Friends, I am looking for advice and recomendations about a data set that
i'd like to analyze where I will measure association by frequencies of
co-occurence.  

Let me explain in more detail. In my experiment participants were shown an
object and asked to choose words that described the item from a list of 50
words.  Responses were either 'yes' or no response was given.  This
procedure was repeated up to 3 times.

I now want to group the word-associates by target item, I have a rough idea
of what I want, but I'm open to suggestions from people who know more about
this than I do.  My plan is to find some method for finding the strength or
description of association between items by examining counts of numbers of
times items co-occured and produce a 'topographical map' where more
frequently listed items are closer together--by analogy, something like an
MDS model where we have a similarity matrix representing how often items are
co-occuring (or is that the answer?)

Anyway, looking forward to your input and suggestions, I think this is an
interesting although maybe standard problem.
Mike Healy