R: _k_-factor correction for chi-squared test statistic

chisqSmallN {semTools} | R Documentation

## k-factor correction for chi-squared test statistic

### Description

Calculate k-factor correction for chi-squared model-fit test statistic to adjust for small sample size.

### Usage

      chisqSmallN(fit0, fit1 = NULL, ...)

### Arguments

`fit0` | The lavaan model object provided after running the `cfa`, `sem`, `growth`, or `lavaan` functions.
`fit1` | Optional additional lavaan model, in which `fit0` is nested. If `fit0` has fewer df than `fit1`, the models will be swapped, still on the assumption that they are nested.
`...` | Additional arguments to the `lavTestLRT` function.

### Details

The k-factor correction (Nevitt & Hancock, 2004) is a global fit index which can be computed by:

kc = 1 - \frac{2 \times P + 4 \times K + 5}{6 \times N}

where N is the sample size when using normal likelihood, or N - 1 when using `likelihood = 'wishart'`.

### Value

A numeric vector including the unadjusted (naive) chi-squared test statistic, the k-factor correction, the corrected test statistic, the df for the test, and the p value for the test under the null hypothesis that the model fits perfectly (or that the 2 models have equivalent fit).

### Author(s)

Terrence D. Jorgensen (University of Amsterdam; TJorgensen314@gmail.com)

### References

Nevitt, J., & Hancock, G. R. (2004). Evaluating small sample approaches for model test statistics in structural equation modeling. Multivariate Behavioral Research, 39(3), 439-478. doi:10.1207/S15327906MBR3903_3

### Examples

    HS.model <- '
        visual  =~ x1 + b1*x2 + x3
        textual =~ x4 + b2*x5 + x6
        speed   =~ x7 + b3*x8 + x9
    '
    fit1 <- cfa(HS.model, data = HolzingerSwineford1939)
    ## test a single model (implicitly compared to a saturated model)
    chisqSmallN(fit1)

    ## fit a more constrained model
    fit0 <- cfa(HS.model, data = HolzingerSwineford1939,
                orthogonal = TRUE)
    ## compare 2 models
    chisqSmallN(fit1, fit0)

[Package semTools version 0.4-14 Index]