Clark Glymour
Department of Philosophy
Carnegie-Mellon University
Costner and The Structure of the Unobserved
Thursday, May 22 at 7:30pm in Physics-Astronomy A110
At the turn of the century Charles Spearman introduced a strategy for
finding unobserved causes by examining statistical constraints satisfied
by their observed effects. Spearman's ideas were developed over the next
thirty years until they were displaced by factor analysis. In the 1960s
and after, Herbert Costner and his collaborators generalized and revived
latent variable model selection based on constraints satisfied by
measured variables. Using directed graphical models, a decade later a
group of us at Carnegie Mellon developed general methods for computing a
class of constraints implied by latent variable models and used them in
a general algorithm for elaborating latent variable models. These
Costner-style search procedures considerably outperform searches based
on fit statistics in LISREL and similar programs. More recently,
Scheines found a constraint based search algorithm that finds
univariate linear latent variable models where they exist, and Scheines
and Spirtes have developed algorithms that, given purified measurement
models for each latent variable, under appropriate conditions describe
the causal relations among the latent variables. Still more recent
results of Richardson's permit the procedures to be extended to
"non-recursive" latent variable models.