chainec | R Documentation |
Calculates chain (indirect) equating coefficients and standard errors using IRT methods.
chainec(r = NULL, direclist, f1 = NULL, f2 = NULL, pths = NULL)
r |
length of the chain, that is the number of forms used for equating
including extremes. It should be at least 3. It does not need to
be specified if argument |
direclist |
an object of the class |
f1 |
the name of the first form of the chain. |
f2 |
the name of the last form of the chain. |
pths |
vector, matrix or data frame containing the path used for equating.
The number of columns
is equal to r and the number of rows is equal to the equatings that
have to be performed.
If |
Equating coefficients perform the conversion from the scale of the first form to the scale of the last form of the path.
An object of class ceqclist
consisting in a list with length
equal to the number of chain equating coefficients computed.
Each component of the list is an object of class ceqc
with components
tab1 |
item parameters of the first form. |
tab2 |
item parameters of the last form. |
tab |
Data frame containing item names ( |
varAll |
covariance matrix of item parameters of all forms used in the chain. |
partial |
partial derivatives of equating coefficients A and B with respect to item parameters. |
A |
equating coefficient A. |
B |
equating coefficient B. |
varAB |
covariance matrix of the equating coefficients. |
commonitem |
list of length r-1 containing the names of common item parameters between adjacent forms. |
ni |
vector containing number of common items between pairs of adjacent forms. |
forms |
names of equated forms. |
method |
the equating method used. |
itmp |
number of item parameters of the IRT model. |
Michela Battauz
Battauz, M. (2013). IRT Test Equating in Complex Linkage Plans. Psychometrika, 78, 464–480.
Battauz, M. (2015). equateIRT: An R Package for IRT Test Equating. Journal of Statistical Software, 68, 1–22.
Kolen, M.J. and Brennan, R.L. (2014). Test equating, scaling, and linking: methods and practices, 3rd ed., New York: Springer
alldirec
, eqc
, itm
, summary.ceqc
, summary.ceqclist
# three-parameter logistic model # direct equating coefficients using the "Stocking-Lord" method data(est3pl) test<-paste("test", 1:5, sep = "") mod3pl <- modIRT(coef = est3pl$coef, var = est3pl$var, names = test, display = FALSE) direclist3pl <- alldirec(mods = mod3pl, method = "Stocking-Lord") # compute all chain equating coefficients of length 4 chainec4 <- chainec(r = 4, direclist = direclist3pl) summary(chainec4) summary(chainec4$test1.test2.test3.test4) # compute all chain equating coefficients of length 4 # where the first form is test1 chainec4.1 <- chainec(r = 4, direclist = direclist3pl, f1 = "test1") summary(chainec4.1) # compute all chain equating coefficients of length 4 # where the first form is test1 and the last form is test4 chainec4.14 <- chainec(r = 4, direclist = direclist3pl, f1 = "test1", f2 = "test4") summary(chainec4.14) # two-parameter logistic model # direct equating coefficients using the "Haebara" method data(est2pl) test<-paste("test", 1:5, sep = "") mod2pl <- modIRT(coef = est2pl$coef, var = est2pl$var, names = test, display = FALSE) direclist2pl <- alldirec(mods = mod2pl, method = "Haebara") # compute chain equating coefficients of a given path pth <- paste("test", c(1,5,4), sep = "") chainec154 <- chainec(direclist = direclist2pl, pths = pth) summary(chainec154) # Rasch model # direct equating coefficients using the "mean-mean" method data(estrasch) test<-paste("test", 1:5, sep = "") modrasch <- modIRT(coef = estrasch$coef, var = estrasch$var, names = test, display = FALSE) direclistrasch <- alldirec(mods = modrasch, method = "mean-mean", all = TRUE) # compute chain equating coefficients of two given paths pth1 <- paste("test", 1:3, sep = "") pth2 <- paste("test", c(1,5,4), sep = "") pths <- rbind(pth1, pth2) chainec1 <- chainec(direclist = direclistrasch, pths = pths) summary(chainec1)
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