R: Class for the Results of Permutation Randomization Tests of...

permuteMeasEq-class {semTools} | R Documentation

## Class for the Results of Permutation Randomization Tests of Measurement Equivalence and DIF

### Description

This class contains the results of tests of Measurement Equivalence and Differential Item Functioning (DIF).

### Objects from the Class

Objects can be created via the `permuteMeasEq` function.

### Slots

`PT`:

  A `data.frame` returned by a call to `parTable` on the constrained model

`modelType`:

  A character indicating the specified `modelType` in the call to `permuteMeasEq`

`ANOVA`:

  A vector indicating the results of the observed chi-squared (difference) test, based on the central chi-squared distribution

`AFI.obs`:

  A vector of observed (changes in) user-selected fit measures

`AFI.dist`:

  The permutation distribution(s) of user-selected fit measures. A `data.frame` with `n.Permutations` rows and one column for each `AFI.obs`.

`AFI.pval`:

  A vector of p values (one for each element in slot `AFI.obs`) calculated using slot `AFI.dist`, indicating the probability of observing a change at least as extreme as `AFI.obs` if the null hypothesis were true

`MI.obs`:

  A `data.frame` of observed Lagrange Multipliers (modification indices) associated with the equality constraints or fixed parameters specified in the `param` argument. This is a subset of the output returned by a call to `lavTestScore` on the constrained model.

`MI.dist`:

  The permutation distribution of the maximum modification index (among those seen in slot `MI.obs$X2`) at each permutation of group assignment or of `covariates`

`extra.obs`:

  If `permuteMeasEq` was called with an `extra` function, the output when applied to the original data is concatenated into this vector

`extra.dist`:

  A `data.frame`, each column of which contains the permutation distribution of the corresponding statistic in slot `extra.obs`

`n.Permutations`:

  An integer indicating the number of permutations requested by the user

`n.Converged`:

  An integer indicating the number of permuation iterations which yielded a converged solution

`n.nonConverged`:

  A vector of length `n.Permutations` indicating how many times group assignment was randomly permuted (at each iteration) before converging on a solution

`n.Sparse`:

  Only relevant with `ordered` indicators when `modelType == "mgcfa"`. A vector of length `n.Permutations` indicating how many times group assignment was randomly permuted (at each iteration) before obtaining a sample with all categories observed in all groups

`oldSeed`:

  An integer vector storing the value of `.Random.seed` before running `permuteMeasEq`. Only relevant when using a parallel/multicore option and the original `RNGkind() != "L'Ecuyer-CMRG"`. This enables users to restore their previous `.Random.seed` state, if desired, by running: `.Random.seed[-1] <- permutedResults@oldSeed[-1]`

### Methods

show

  `signature(object = "permuteMeasEq"):` The `show` function is used to summarize the results of the multiparameter omnibus test of measurement equivalence, using the user-specified AFIs. The parametric chi-squared (difference) test is also displayed.

summary

  `signature(object = "permuteMeasEq", alpha = .05, nd = 3, extra = FALSE):` The summary function prints the same information from the `show` method, but when `extra = FALSE` (the default) it also provides a table summarizing any requested follow-up tests of DIF using modification indices in slot `MI.obs`. The user can also specify an `alpha` level for flagging modification indices as significant, as well as `nd` (the number of digits displayed). For each modification index, the p value is displayed using a central chi-squared distribution with the df shown in that column. Additionally, a p value is displayed using the permutation distribution of the maximum index, which controls the familywise Type I error rate in a manner similar to Tukey's studentized range test. If any indices are flagged as significant using the `tukey.p.value`, then a message is displayed for each flagged index. The invisibly returned `data.frame` is the displayed table of modification indices, unless `permuteMeasEq` was called with `param = NULL`, in which case the invisibly returned object is `object`. If `extra = TRUE`, the permutation-based p values for each statistic returned by the `extra` function are displayed and returned in a `data.frame` instead of the modification indices requested in the `param` argument.

hist

  `signature(x = "permuteMeasEq", ..., AFI, alpha = .05, nd = 3, printLegend = TRUE, legendArgs = list(x = "topleft")):` The `hist` function provides a histogram for the permutation distribution of the specified `AFI`, including observed and critical values from the specified `alpha` level. Distributions of modification indices and any extra output are not available with this method, but they can be created manually by accessing the distributions in slot `MI.dist` or `extra.dist`. The user can also specify additional graphical parameters to `hist` via `...`, as well as pass a list of arguments to an optional `legend` via `legendArgs`. If `AFI = "chisq"`, then the probability density and critical value from the central chi-squared distribution are also included in the plot. If the user wants more control over customization, `hist` returns a list of `length == 2`, containing the arguments for the call to `hist` and the arguments to the call for `legend`, respectively. This list may facilitate creating a customized histogram of `AFI.dist`, `MI.dist`, or `extra.dist`.

### Author(s)

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

### See Also

`permuteMeasEq`

### Examples

    # See the example from the permuteMeasEq function

[Package semTools version 0.4-14 Index]