Was it Bollen's book? In general, I think the value of SEM is, given some assumptions, in identifying which out of a set of causal theories are the best explana

Was it Bollen's book? In general, I think the value of SEM is, given some assumptions, in identifying which out of a set of causal theories are the best explanations of some data. In practice this usually turns out to be a set of causal theories that are indistinguishable, given the data, and some that are clearly worse. With latent variables, they're used all over in psychology to represent constructs (e.g. happiness, extroversion, IQ).