The function tam.modelfit computes several model fit statistics. It includes the Q3 statistic (Yen, 1984) and an adjusted variant of it (see Details). Effect sizes of model fit (MADaQ3, MADRESIDCOV, SRMR) are also available.
● Data Source:
CranContrib
● Keywords: Model fit, Q3 statistic, summary
● Alias: summary.tam.modelfit, tam.modelfit
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This function parses a so called tammodel which is a string used for model estimation in TAM. The function is based on the lavaan syntax and operates at the extension lavaanify.IRT.
● Data Source:
CranContrib
● Keywords: Model specification, TAM language
● Alias: tamaanify
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This function creates a Wright map and works as a wrapper to the wrightMap function in the WrightMap package. The arguments thetas and thresholds are automatically generated from fitted objects in TAM.
Converts a θ score into an unweighted true score τ ( θ) = ∑_i ∑_h h P_i ( θ ) . In addition, a weighted true score τ ( θ) = ∑_i ∑_h q_{ih} P_i ( θ ) can also be computed by specifying item-category weights q_{ih} in the matrix Q.
The anova function compares two models estimated of class tam, tam.mml or tam.mml.3pl using a likelihood ratio test. The logLik function extracts the value of the log-Likelihood.
This function approximates a fitted item response model by a linear confirmatory factor analysis. I.e., given item response functions, the expectation E(X_i | θ_1 , … , θ_D) is linearly approximated by a_{i1} θ _1 + … + a_{iD} θ_D. See Vermunt and Magidson (2005) for details.
This function is a convenience wrapper function for several item response models in TAM. Using the tamaanify framework, multidimensional item response models, latent class models, located and ordered latent class models and mixture item response models can be estimated.
● Data Source:
CranContrib
● Keywords: Model specification, TAM language
● Alias: print.tamaan, summary.tamaan, tamaan
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