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Package incompatibility - ltm RRS feed

  • Question

  • In my computer, with revomath installed, the script:

    install.packages("ltm")
    library(ltm)
    data(LSAT)
    IRTModel2 = tpm(LSAT, type="latent.trait", IRT.param = TRUE)
    coef(IRTModel2)

    estimates the Item 3 coefficients incorrectly.

    Gussng Dffclt Dscrmn Item 1 0.06927 -3.3918 0.7862 Item 2 0.02506 -1.3071 0.7279 Item 3 0.37295 0.6536 23.1930 Item 4 0.03441 -1.8754 0.6526 Item 5 0.03093 -2.9280 0.6939

    Without RevoMath I do get the correct values:

            Gussng Dffclt Dscrmn
    Item 1 0.03739 -3.296 0.8286
    Item 2 0.07771 -1.145 0.7604
    Item 3 0.01178 -0.249 0.9016
    Item 4 0.03529 -1.766 0.7007
    Item 5 0.05316 -2.990 0.6658

    Wednesday, August 17, 2016 4:29 PM