Report which Mplus executable will be used, its version, and any demo-version limits. Call this first when a run fails for reasons that look like the installation rather than the model.

Mplus syntax reference by topic: overview, data, variable, analysis, model, mediation, cfa, invariance, growth, mixture, multilevel, output, fit, montecarlo, errors, demo. Call with no topic to list them. Use it before writing syntax for a model family you have not written recently.

Convert a CSV, Excel, SPSS (.sav), Stata (.dta) or parquet file into an Mplus .dat file: numeric only, no header, missing values flagged, names cut to 8 characters. Returns the DATA and VARIABLE block to paste into an input file, plus a per-variable summary and a note of anything that was renamed or recoded.

Write Mplus input syntax for a standard model family (cfa, efa, path, sem, mediation, growth, lpa, lca, invariance, twolevel, custom). Returns the syntax as text - it does not run it. Read it, adjust it, then pass it to run_syntax. Anything the template does not cover goes in model_extra, analysis_extra or model_constraint.

Write Mplus input syntax to a file, run it, and summarise the output. Long lines are folded to the 90-character limit first. The .inp and .out stay on disk. Use include to ask for more of the output than the default fit table, parameter estimates and warnings.

Run an Mplus input file that already exists on disk and summarise the output. Use this for .inp files written by hand or by the Mplus editor.

Summarise an Mplus .out file that already exists: status, warnings, fit, parameter estimates, and whatever else include asks for. Use it on output produced outside this server, or to re-read a run without repeating it.

Return one section of an .out file verbatim, for anything the summary does not parse - TECH1, TECH4, residuals, sample statistics, random-start loglikelihoods. Call without section to list the sections in the file.

Put the fit statistics of several .out files side by side - class enumeration, measurement invariance, nested model comparisons. With chisq_diff it also runs the chi-square difference test between consecutive models, scaled for MLR when Mplus reported a scaling correction factor.

Read the file a SAVEDATA command wrote - factor scores, class probabilities, most likely class membership - using the column layout Mplus recorded at the end of the .out file. Optionally write it out as a CSV for use in R or Excel.