I think it was in the 70's, most likely at a joint meeting of the 
Classification and Psychometric Societies, that I saw a presentation 
that showed each of the Lazarfeld approaches was formally identical to 
an approach that was called by some other name in psych.

Lazarfeld's terms were Latent Class Analysis, Latent Trait Analysis, and 
Latent Profile Analysis.

Is my memory right?   Are there formally equivalent approaches that use 
alternative terminology for each of these?

Or are these completely different approaches to finding groups / sets / 
clusters of dichotomous variables, continuous variables, and entiities / 
cases / objects respectively?

Art Kendall
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