Scoring
Relates number-correct scores on two forms.
score(obj, ...) ## S3 method for class 'eqc' score(obj, method = "TSE", D = 1, scores = NULL, se = TRUE, nq = 30, w = 0.5, theta = NULL, weights = NULL, anchor.type = "internal", ...) ## S3 method for class 'eqclist' score(obj, link = NULL, method = "TSE", D = 1, scores = NULL, se = TRUE, nq = 30, w = 0.5, theta = NULL, weights = NULL, anchor.type = "internal", ...) ## S3 method for class 'ceqc' score(obj, method = "TSE", D = 1, scores = NULL, se = TRUE, nq = 30, w = 0.5, theta = NULL, weights = NULL, anchor.type = "internal", ...) ## S3 method for class 'ceqclist' score(obj, path = NULL, method = "TSE", D = 1, scores = NULL, se = TRUE, nq = 30, w = 0.5, theta = NULL, weights = NULL, anchor.type = "internal", ...) ## S3 method for class 'meqc' score(obj, link = NULL, method = "TSE", D = 1, scores = NULL, se = TRUE, bistype = NULL, nq = 30, w = 0.5, theta = NULL, weights = NULL, anchor.type = "internal", ...)
obj: output object from functions direc, alldirec, chainec or bisectorec.link: a character string with the names of the two forms being linked separated by a dot (e.g. "test1.test3"). Necessary if obj is output of functions alldirec or bisectorec.path: a character string with the names of the forms that constitute the path separated by a dot (e.g. "test1.test2.test3"). Necessary if obj is output of function chainec.method: the scoring method to be used. This should be one of "TSE" (the default) for true score equating or "OSE" for observed score equating.D: constant D of the IRT model used to estimate item parameters.scores: integer values to be converted.se: logical; is TRUE standard errors of equated scores are computed.bistype: bisector type. It should be specified when obj is an output object from function bisectorec. It should be weighted or unweighted. It can be NULL if only one type was computed by function bisectorec.nq: number of quadrature points used to approximate integrals with observed score equating. Used only if arguments theta and weights are NULL.w: synthetic weight for population 1. It should be a number between 0 and 1.theta: vector of ability values used to approximate integrals with observed score equating.weights: vector of weights used to approximate integrals with observed score equating.anchor.type: The anchor type, which can be "internal" or "external". External anchors are not implemented for bisector equating coefficients. See details....: further arguments passed to or from other methods.If anchor.type is internal, the common items are used for computing the scores; if it is external, the common items are used for computing the equating coefficients but not for computing the scores. External anchors are not implemented for bisector equating coefficients because it is possible that all items are used as achors in one of the paths considered.
This function computes standard error of equated scores with the observed score equating method using for the description of , and for
(see Ogasawara, 2003).
A data frame containing theta values (only for true score equating), scores in the form chosen as base, equated scores, and standard errors of equated scores.
Kolen, M.J. and Brennan, R.L. (2014). Test equating, scaling, and linking: methods and practices, 3nd ed., New York: Springer.
Ogasawara, H. (2001). Item response theory true score equatings and their standard errors. Journal of Educational and Behavioral Statistics, 26 , 31--50.
Ogasawara, H. (2003). Asymptotic standard errors of IRT observed-score equating methods. Psychometrika, 68 , 193--211.
Michela Battauz
alldirec, bisectorec, chainec, direc
# the following code uses item parameter estimates previously obtained # for examples that start from item response data see function modIRT # two-parameter logistic model data(est2pl) test<-paste("test", 1:5, sep = "") mod2pl <- modIRT(coef = est2pl$coef, var = est2pl$var, names = test, display = FALSE) # direct equating coefficients between forms 1 and 2 using the Haebara method l12 <- direc(mods = mod2pl, which = c(1,2), method = "Haebara") # scoring using direct equating coefficients and the true score equating method score(l12) # scoring using direct equating coefficients and the observed score equating method score(l12, method = "OSE") # specify only scores from 10 to 15 score(l12, method = "OSE", scores = 10:15) # external anchors and true score equating method score(l12, anchor.type = "external") # external anchors and observed score equating method score(l12, method = "OSE", anchor.type = "external") # all direct equating coefficients using the Haebara method direclist2pl <- alldirec(mods = mod2pl, method = "Haebara") # scoring using direct equating coefficients and the true score equating method score(direclist2pl, link = "test1.test2") # compute chain equating coefficients for path 1,2,3,4 pth1 <- paste("test", 1:4, sep = "") chainec1 <- chainec(direclist = direclist2pl, pths = pth1) # compute chain equating coefficients for path 1,5,4 pth2 <- paste("test", c(1,5,4), sep = "") chainec2 <- chainec(direclist = direclist2pl, pths = pth2) # scoring using chain equating coefficients and the true score equating method for score 12 score(chainec1, path = "test1.test2.test3.test4", scores = 12) score(chainec2, path = "test1.test5.test4", scores = 12) # scoring using chain equating coefficients, true score equating and external anchors score(chainec1, path = "test1.test2.test3.test4", anchor.type = "external") # scoring using chain equating coefficients, observed score equating and external anchors score(chainec1, path = "test1.test2.test3.test4", method = "OSE", anchor.type = "external") # create a list of objects of class ceqc ecall <- c(chainec1, chainec2) # compute bisector and weighted bisector coefficients allec <- bisectorec(ecall = ecall, weighted = TRUE, unweighted = TRUE) # scoring using weighted bisector equating coefficients and the true score # equating method for score 12 score(allec, bistype = "weighted", link = "test1.test4", scores = 12)
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