psem is used to unite a list of structural equations into a single
structural equation model.
psem(...)A list of structural equations
Returns an object of class psem
psem takes a list of structural equations, which can be model objects
of classes: lm, glm, gls, pgls, sarlm, lme, glmmPQL, lmerMod,
lmerModLmerTest, glmerMod.
It also takes objects of class formula, formula.cerror, corresponding
to additional variables to be included in the tests of directed separation
(X ~ 1) or correlated errors (X1 %~~% X2).
The function optionally accepts data objects of classes: matrix,
data.frame, SpatialPointsDataFrame, comparative.data, or these are derived
internally from the structural equations.