A character string (typically between single quotes)
containing one or more equality constraints. See examples for more details.
verbose
Logical. If TRUE, print out the restriction matrix
and the estimated restricted values.
Details
The constraints are specified using the "==" operator. Both
the left-hand side and the right-hand side of the equality can contain
a linear combination of model parameters, or a constant (like zero).
The model parameters must be specified by their user-specified labels.
Names of defined parameters (using the ":=" operator) can be
included too.
Value
A list containing three elements: the Wald test statistic (stat), the
degrees of freedom (df), and a p-value under the chi-square distribution
(p.value).
Examples
HS.model <- '
visual =~ x1 + b1*x2 + x3
textual =~ x4 + b2*x5 + x6
speed =~ x7 + b3*x8 + x9
'
fit <- cfa(HS.model, data=HolzingerSwineford1939)
# test 1: test about a single parameter
# this is the 'chi-square' version of the
# z-test from the summary() output
lavTestWald(fit, constraints = "b1 == 0")
# test 2: several constraints
con = '
2*b1 == b3
b2 - b3 == 0
'
lavTestWald(fit, constraints = con)