kfa (version 0.2.2)

kfa: Conducts k-fold cross validation for factor analysis

Description

The function splits the data into k folds where each fold contains training data and test data. For each fold, exploratory factor analyses (EFAs) are run on the training data. The structure for each model is transformed into lavaan-compatible confirmatory factor analysis (CFA) syntax. The CFAs are then run on the test data.

Usage

kfa(
  data,
  variables = names(data),
  k = NULL,
  m = floor(length(variables)/4),
  seed = 101,
  cores = NULL,
  custom.cfas = NULL,
  power.args = list(rmsea0 = 0.05, rmseaA = 0.08),
  rotation = "oblimin",
  simple = TRUE,
  min.loading = NA,
  single.item = "none",
  ordered = FALSE,
  estimator = NULL,
  missing = "listwise",
  ...
)

Value

An object of class "kfa", which is a four-element list:

• cfas lavaan CFA objects for each k fold

• cfa.syntax syntax used to produce CFA objects

• model.names vector of names for CFA objects

• efa.structures all factor structures identified in the EFA

Arguments

data

a data.frame containing the variables (i.e., items) to factor analyze

variables

character vector of column names in data indicating the variables to factor analyze. Default is to use all columns.

k

number of folds in which to split the data. Default is NULL which determines k via find_k.

m

integer; maximum number of factors to extract. Default is 4 items per factor.

seed

integer passed to set.seed when randomly selecting cases for each fold.

cores

integer; number of CPU cores to use for parallel processing. Default is detectCores - 1.

custom.cfas

a single object or named list of lavaan syntax specifying custom factor model(s).

power.args

named list of arguments to pass to find_k and findRMSEAsamplesize when conducting power analysis to determine k.

rotation

character (case-sensitive); any rotation method listed in rotations in the GPArotation package. Default is "oblimin".

simple

logical; Should the perfect simple structure be returned (default) when converting EFA results to CFA syntax? If FALSE, items can cross-load on multiple factors.

min.loading

numeric between 0 and 1 indicating the minimum (absolute) value of the loading for a variable on a factor when converting EFA results to CFA syntax. Must be specified when simple = FALSE.

single.item

character indicating how single-item factors should be treated. Use "keep" to keep them in the model when generating the CFA syntax or "none" (default) indicating the CFA syntax should not be generated for this model and "" is returned.

ordered

logical; Should items be treated as ordinal and the polychoric correlations used in the factor analysis? When FALSE (default) the Pearson correlation matrix is used. A character vector of item names is also accepted to prompt estimation of the polychoric correlation matrix.

estimator

if ordered = FALSE, the default is "MLMVS". If ordered = TRUE, the default is "WLSMV". See lavOptions for other options.

missing

default is "listwise". See lavOptions for other options.

...

other arguments passed to lavaan functions. See lavOptions.

Details

In order for custom.cfas to be tested along with the EFA identified structures, each model supplied in custom.cfas must include all variables in lavaan-compatible syntax.

Deciding an appropriate m can be difficult, but is consequential for the possible factor structures to examine, the power analysis to determine k, and overall computation time. The n_factors function in the parameters package can assist with this decision.

When converting EFA results to CFA syntax (via efa_cfa_syntax), the simple structure is defined as each variable loading onto a single factor. This is determined using the largest factor loading for each variable. When simple = FALSE, variables are allowed to cross-load on multiple factors. In this case, all pathways with loadings above the min.loading are retained. However, allowing cross-loading variables can result in model under-identification. The efa_cfa_syntax) function conducts an identification check (i.e., identified = TRUE) and under-identified models are not run in the CFA portion of the analysis.

Examples

# simulate data based on a 3-factor model with standardized loadings
sim.mod <- "f1 =~ .7*x1 + .8*x2 + .3*x3 + .7*x4 + .6*x5 + .8*x6 + .4*x7
                f2 =~ .8*x8 + .7*x9 + .6*x10 + .5*x11 + .5*x12 + .7*x13 + .6*x14
                f3 =~ .6*x15 + .5*x16 + .9*x17 + .4*x18 + .7*x19 + .5*x20
                f1 ~~ .2*f2
                f2 ~~ .2*f3
                f1 ~~ .2*f3
                x9 ~~ .2*x10"
set.seed(1161)
sim.data <- simstandard::sim_standardized(sim.mod, n = 900,
                                          latent = FALSE,
                                          errors = FALSE)[c(2:9,1,10:20)]

# include a custom 2-factor model
custom2f <- paste0("f1 =~ ", paste(colnames(sim.data)[1:10], collapse = " + "),
                   "\nf2 =~ ",paste(colnames(sim.data)[11:20], collapse = " + "))

# \donttest{
mods <- kfa(data = sim.data,
            k = NULL, # prompts power analysis to determine number of folds
            cores = 2,
            custom.cfas = custom2f)
            # }