solomonR 0.2.0

solomonR 0.2.0

The first substantial release of solomonR, an R package for analyzing and
teaching the Solomon four-group experimental design.

This release expands solomonR from its initial implementation into a
multi-framework Solomon analysis toolkit spanning historical procedures,
modern regression, randomization inference, maximum likelihood, and
structural equation modeling.

Highlights

Historical Solomon analysis

• Full historical Tests A-I workflow
• Solomon decision-path reporting
• ANCOVA, gain-score, repeated-measures, and posttest-only procedures
• Explicit cautions regarding historical conditional-testing strategies

Modern observed-variable analysis

• Unified Solomon GLM
• Equal-weighted average treatment effect
• Pretest sensitization interaction
• Treatment effects within pretested and unpretested participants
• HC3 heteroskedasticity-robust covariance estimation
• CR2 cluster-robust covariance estimation
• Wald-based partial R² for Gaussian models

Randomization inference

• Treatment-label permutation within pretest-assignment strata
• Studentized permutation statistics
• Finite Monte Carlo p-value correction
• Permutation-distribution plotting

Maximum likelihood

• Full-information Solomon-specific maximum-likelihood analysis
• Structural pretest absence handled as part of the experimental design

Structural equation modeling

• Observed-variable Solomon SEM
• ANCOVA-style SEM
• Latent-variable Solomon SEM
• Measurement-invariance controls
• Scalar-invariance safeguards for latent mean comparisons
• Explicit convergence checks

Documentation and reliability

• Expanded classic and modern analysis vignettes
• Rebuilt README and package documentation
• Extensive automated tests
• Cross-platform GitHub Actions checks
• R CMD check: 0 errors, 0 warnings, 0 notes

Installation

The release can be installed directly from GitHub with:

install.packages("pak")
pak::pak("JUhalt/solomonR@v0.2.0")