summary.ltm {ltm} | R Documentation |
Summarizes the fit of an ltm
object.
## S3 method for class 'ltm': summary(object, robust.se = FALSE, ...)
object |
an object inheriting from class ltm . |
robust.se |
logical; if TRUE robust estimation of standard errors is used, based on the sandwich estimator. |
... |
additional argument; currently none is used. |
An object of class summ.ltm
with components,
coefficients |
the estimated coefficients' table. |
Var.betas |
the approximate covariance matrix for the estimated parameters. |
logLik |
the log-likelihood of object . |
AIC |
the AIC for object . |
BIC |
the BIC for object . |
max.sc |
the maximum absolute value of the score vector at convergence. |
conv |
the convergence identifier returned by optim . |
counts |
the counts argument returned by optim . |
call |
the matched call of object . |
ltn.struct |
a character vector describing the latent structure used in object . |
control |
the values used in the control argument in the fit of object . |
nitems |
the number of items in the data set. |
For the parameters that have been constrained, the standard errors and z-values are printed as NA
.
When the coefficients' estimates are reported under the usual IRT parameterization (i.e., IRT.param = TRUE
in the call of ltm
), their standard errors are calculated using the Delta method.
Dimitris Rizopoulos dimitris.rizopoulos@med.kuleuven.be
## One factor model using the WIRS data; ## results are reported under the IRT ## parameterization m <- ltm(Wirs ~ z1, IRT = TRUE) summary(m) summary(m, TRUE)