MplusAutomation (version 0.6-1)

extractModelParameters: Extract model parameters from MODEL RESULTS section.

Description

Extracts the model parameters from the MODEL RESULTS section of one or more Mplus output files. If a particular output file has more than one results section (unstandardized, stdyx, stdy, and/or std), a list will be returned. If the target is a directory, all .out files therein will be parsed and a single list will be returned, where the list elements are named by the output file name. Returned parameters often include the parameter estimate, std. err, param/s.e., and two-tailed p-value.

Usage

extractModelParameters(target = getwd(),
    recursive = FALSE, filefilter, dropDimensions = FALSE,
    resultType)

Arguments

target

the directory containing Mplus output files (.out) to parse OR the single output file to be parsed. May be a full path, relative path, or a filename within the working directory. Defaults to the current working directory. Example: C:/User

recursive

optional. If TRUE, parse all models nested in subdirectories within target. Defaults to FALSE.

filefilter

a Perl regular expression (PCRE-compatible) specifying particular output files to be parsed within directory. See regex or http://www.pcre.org/pcre.txt for details about regular expression syntax.

dropDimensions

Relevant only for multi-file parsing. If TRUE, then if only one output section (usually unstandardized) is present for all files in the parsed list, then eliminate the second-level list (which contains elements for each output section

resultType

N.B.: this parameter is deprecated and will be removed in a future version. The new default is to extract all results that are present and return a list (see below for details). resultType specified the results section to extract. If

Value

• If target is a single file, a list containing unstandardized and standardized results will be returned. If all standardized solutions are available, the list element will be named: unstandardized, stdyx.standardized, stdy.standardized, and std.standardized. If confidence intervals are output using OUTPUT:CINTERVAL, then a list element named ci.unstandardized will be included. Each of these list elements is a data.frame containing relevant model parameters.

  If target is a directory, a list will be returned, where each element contains the results for a single file, and the top-level elements are named after the corresponding output file name. Each element within this list is itself a list, with elements as in the single file case above.

  The core data.frame for each MODEL RESULTS section typically has the following structure:

• paramHeader
  The header that begins a given parameter set. Example: "FACTOR1 BY"
• param
  The particular parameter being measured (within paramHeader). Example: "ITEM1"
• est
  Parameter estimate value.
• se
  Standard error of the estimate
• est_se
  Quotient of est/se, representing z-test/t-test in large samples
• pval
  Two-tailed p-value for the est_se quotient.
• In the case of output from Bayesian estimation (ESTIMATOR=BAYES), the data.frame will contain a different set of variables, including some of the above, as well as
• posterior_sd
  Posterior standard deviation of the estimate.
• lower_2.5ci
  Lower 2.5 percentile of the estimate.
• upper_2.5ci
  Upper 2.5 percentile (aka 97.5 percentile) of the estimate.
• Also note that the pval column for Bayesian output represents a one-tailed estimate.

  In the case of output from a Monte Carlo study (MONTECARLO: and MODEL POPULATION:), the data.frame will contain a different set of variables, including some of the above, as well as

• population
  Population parameter value.
• average
  Average parameter estimate across replications.
• population_sd
  Standard deviation of parameter value in population across replications.
• average_se
  Average standard error of estimated parameter value across replications.
• mse
  Mean squared error.
• cover_95
  Proportion of replications whose 95% confidence interval for the parameter includes the population value.
• pct_sig_coef
  Proportion of replications for which the two-tailed significance test of the parameter is significant (p < .05).
• In the case of confidence interval output (OUTPUT:CINTERVAL), the list element ci.unstandardized will contain a different set of variables, including some of the above, as well as
• low.5
  Lower 0.5% CI estimate.
• low2.5
  Lower 2.5% CI estimate.
• low5
  Lower 5% CI estimate.
• est
  Parameter estimate value.
• up5
  Upper 5% (i.e., 95%) CI estimate.
• up2.5
  Upper 2.5% (i.e., 97.5%) CI estimate.
• up.5
  Upper 0.5% (i.e., 99.5%) CI estimate.
• If the model contains multiple latent classes, an additional variable, LatentClass, will be included, specifying the latent class number. Also, the Categorical Latent Variables section will be included as LatentClass "Categorical.Latent.Variables."

  If the model contains multiple groups, Group will be included.

  If the model contains two-level output (between/within), BetweenWithin will be included.

See Also

extractModelSummaries

Examples

ex3.14 <- extractModelParameters(
	"C:/Program Files/Mplus/Mplus Examples/User's Guide Examples/ex3.14.out")