make_sem_ram converts SEM arrow notation to ram describing SEM parameters
make_sem_ram(sem, variables, quiet = FALSE, covs = variables)An S3-class "sem_ram" containing:
modelOutput from specifyEquations or specifyModel
that defines paths and parameters
ramreticular action module (RAM) describing dependencies
structural equation model structure, passed to either specifyModel
or specifyEquations and then parsed to control
the set of path coefficients and variance-covariance parameters
A character vector listing the set of variables
if FALSE, the default, then the number of input lines is reported and
a message is printed suggesting that specifyEquations or cfa be used.
optional: a character vector of one or more elements, with each element
giving a string of variable names, separated by commas. Variances and covariances
among all variables in each such string are added to the model. For confirmatory
factor analysis models specified via cfa, covs defaults to all of
the factors in the model, thus specifying all variances and covariances among these factors.
Warning: covs="x1, x2" and covs=c("x1", "x2") are not
equivalent: covs="x1, x2" specifies the variance of x1, the variance
of x2, and their covariance, while covs=c("x1", "x2") specifies
the variance of x1 and the variance of x2 but not their covariance.