Description Usage Arguments Value References See Also Examples
Computes gradient (GR), likelihood ratio (LR), Rao score (RS) and Wald (W) test statistics for hypothesis of equality of item parameters between two groups of persons against a twosided alternative that at least one item parameter differs between the two respected groups.
1  invar_test(X, splitcr = "median", model = "RM")

X 
data matrix. 
splitcr 
split criterion which is either "mean", "median" or a numeric vector x.

model 
RM, PCM, RSM 
A list of test statistics, degrees of freedom, and pvalues.
test 
a numeric vector of gradient (GR), likelihood ratio (LR), Rao score (RS), and Wald test statistics. 
df 
degrees of freedom. 
pvalue 
a numeric vector of corresponding pvalues. 
call 
the matched call. 
Draxler, C. (2010). Sample Size Determination for Rasch Model Tests. Psychometrika, 75(4), 708–724.
Draxler, C., & Alexandrowicz, R. W. (2015). Sample Size Determination Within the Scope of Conditional Maximum Likelihood Estimation with Special Focus on Testing the Rasch Model. Psychometrika, 80(4), 897–919.
Draxler, C., Kurz, A., & Lemonte, A. J. (2019). The Gradient Test and its Finite Sample Size Properties in a Conditional Maximum Likelihood and Psychometric Modeling Context. Submitted for publication.
Glas, C. A. W., & Verhelst, N. D. (1995a). Testing the Rasch Model. In G. H. Fischer & I. W. Molenaar (Eds.), Rasch Models: Foundations, Recent Developments, and Applications (pp. 69–95). New York: Springer.
Glas, C. A. W., & Verhelst, N. D. (1995b). Tests of Fit for Polytomous Rasch Models. In G. H. Fischer & I. W. Molenaar (Eds.), Rasch Models: Foundations, Recent Developments, and Applications (pp. 325352). New York: Springer.
Lemonte, A. J. (2016). The Gradient Test. Another LikelihoodBased Test. London:Academic Press.
Terrell, G. R. (2002). The Gradient Statistic. Computing Science and Statistics, 34(34), 206–215.
change_test
, and LLTM_test
.
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