1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
|
% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/fitIndices.R
\name{chisqSmallN}
\alias{chisqSmallN}
\title{Small-\emph{N} correction for \eqn{chi^2} test statistic}
\usage{
chisqSmallN(fit0, fit1 = NULL, smallN.method = if (is.null(fit1))
c("swain", "yuan.2015") else "yuan.2005", ..., omit.imps = c("no.conv",
"no.se"))
}
\arguments{
\item{fit0, fit1}{\link[lavaan:lavaan-class]{lavaan::lavaan} or \link[lavaan.mi:lavaan.mi-class]{lavaan.mi::lavaan.mi} object(s)}
\item{smallN.method}{\code{character} indicating the small-\emph{N}
correction method to use. Multiple may be chosen (all of which assume
normality), as described in Shi et al. (2018):
\code{c("swain","yuan.2015","yuan.2005","bartlett")}. Users may also
simply select \code{"all"}.}
\item{\dots}{Additional arguments to the \code{\link[lavaan:lavTestLRT]{lavaan::lavTestLRT()}} or
\code{\link[lavaan.mi:lavTestLRT.mi]{lavaan.mi::lavTestLRT.mi()}} functions. Ignored when \code{is.null(fit1)}.}
\item{omit.imps}{\code{character} vector specifying criteria for omitting
imputations from pooled results. Ignored unless \code{fit0} (and
optionally \code{fit1}) is a \link[lavaan.mi:lavaan.mi-class]{lavaan.mi::lavaan.mi} object. See
\code{\link[lavaan.mi:lavTestLRT.mi]{lavaan.mi::lavTestLRT.mi()}} for a description of options and defaults.}
}
\value{
A \code{list} of \code{numeric} vectors: one for the originally
requested statistic(s), along with one per requested \code{smallN.method}.
All include the the (un)adjusted test statistic, its \emph{df}, and the
\emph{p} value for the test under the null hypothesis that the model fits
perfectly (or that the 2 models have equivalent fit).
The adjusted chi-squared statistic(s) also include(s) the scaling factor
for the small-\emph{N} adjustment.
}
\description{
Calculate small-\emph{N} corrections for \eqn{chi^2} model-fit test
statistic to adjust for small sample size (relative to model size).
}
\details{
Four finite-sample adjustments to the chi-squared statistic are currently
available, all of which are described in Shi et al. (2018). These all
assume normally distributed data, and may not work well with severely
nonnormal data. Deng et al. (2018, section 4) review proposed small-\emph{N}
adjustments that do not assume normality, which rarely show promise, so
they are not implemented here. This function currently will apply
small-\emph{N} adjustments to scaled test statistics with a warning that
they do not perform well (Deng et al., 2018).
}
\examples{
HS.model <- '
visual =~ x1 + b1*x2 + x3
textual =~ x4 + b2*x5 + x6
speed =~ x7 + b3*x8 + x9
'
fit1 <- cfa(HS.model, data = HolzingerSwineford1939[1:50,])
## test a single model (implicitly compared to a saturated model)
chisqSmallN(fit1)
## fit a more constrained model
fit0 <- cfa(HS.model, data = HolzingerSwineford1939[1:50,],
orthogonal = TRUE)
## compare 2 models
chisqSmallN(fit1, fit0)
}
\references{
Deng, L., Yang, M., & Marcoulides, K. M. (2018). Structural equation
modeling with many variables: A systematic review of issues and
developments. \emph{Frontiers in Psychology, 9}, 580.
\doi{10.3389/fpsyg.2018.00580}
Shi, D., Lee, T., & Terry, R. A. (2018). Revisiting the model
size effect in structural equation modeling.
\emph{Structural Equation Modeling, 25}(1), 21--40.
\doi{10.1080/10705511.2017.1369088}
}
\author{
Terrence D. Jorgensen (University of Amsterdam; \email{TJorgensen314@gmail.com})
}
|
