umxEquate: Equate two or more paths
In addition to dropping or adding parameters, a second common task in modeling is to equate parameters. umx provides a convenience function to equate parameters by setting one or more parameters (the "slave" set) equal to one or more "master" parameters. These parameters are picked out via their labels, and setting two or more parameters to have the same value is accomplished by setting the slave(s) to have the same label(s) as the master parameters, thus constraining them to take the same value during model fitting.
umxEquate( model, a, b, newlabels = NULL, free = c(TRUE, FALSE, NA), verbose = FALSE, name = NULL, autoRun = FALSE, tryHard = c("no", "yes", "ordinal", "search"), comparison = TRUE, master = NULL, slave = NULL )
model |
An |
a |
one or more labels to equate with those in the "b" set. |
b |
one or more labels to equate with those in the 'a' set. (if 'newlabels' is NULL, labels will be set to 'a' list). |
newlabels |
(optional) list of new labels for the equated parameters. |
free |
Must the parameter(s) initially be free? (default = TRUE) |
verbose |
Whether to give verbose feedback (default = TRUE) |
name |
name for the returned model (optional: Leave empty to leave name unchanged) |
autoRun |
Whether to run the model (default), or just to create it and return without running. |
tryHard |
Default ('no') uses normal mxRun. "yes" uses mxTryHard. Other options: "ordinal", "search" |
comparison |
Compare the new model to the old (if updating an existing model: default = TRUE) |
master |
synonym for 'a' |
slave |
synonym for 'b' |
note: In addition to using this method to equating parameters, you can also equate one parameter to another by setting its label to the "square bracket" address of the master, e.g. "a[r,c]".
Tip: To find labels of free parameters use umxGetParameters()
with free = TRUE
Tip: To find labels by name, use the regex parameter of umxGetParameters()
Other Model Summary and Comparison:
umxCompare()
,
umxMI()
,
umxReduce()
,
umxSetParameters()
,
umxSummary()
,
umx
require(umx) data(demoOneFactor) manifests = names(demoOneFactor) m1 = umxRAM("One Factor", data = demoOneFactor, type = "cov", umxPath("G", to = manifests), umxPath(var = manifests), umxPath(var = "G", fixedAt = 1) ) # By default, umxEquate just equates master and slave labels: doesn't run model m2 = umxEquate(m1, a = "G_to_x1", b = "G_to_x2", name = "Eq x1 x2 loadings") # Set autoRun = TRUE and comparison = TRUE to run and output a comparison m2 = umxEquate(m1, autoRun = TRUE, comparison = TRUE, name = "Eq_x1_x2", a = "G_to_x1", b = "G_to_x2" ) # rename the equated paths m2 = umxEquate(m1, autoRun = TRUE, comparison = TRUE, name = "Eq_x1_x2", a = "G_to_x1", b = "G_to_x2", newlabels = c("equated") ) parameters(m2)
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