cdist | R Documentation |
Calculates conditional means, variances, skewnesses and kurtoses for observed and estimated bivariate probability distributions of test scores.
cdist(est, obs, xscores, ascores)
est |
Matrix of estimated bivariate score probabilities. |
obs |
Matrix of observed bivariate score probabilities. |
xscores |
Optional argument to specify the score vector for test X. |
ascores |
Optional argument to specify the score vector for test A. |
An object of class 'cdist' containing the following slots
est1 |
Matrix of conditional means, variances, skewnesses and kurtoses of X given A for the estimated score distribution. |
est2 |
Matrix of conditional means, variances, skewnesses and kurtoses of A given X for the estimated score distribution. |
obs1 |
Matrix of conditional means, variances, skewnesses and kurtoses of X given A for the observed score distribution. |
obs2 |
Matrix of conditional means, variances, skewnesses and kurtoses of A given X for the observed score distribution. |
bjorn.andersson@statistik.uu.se
kenny.branberg@stat.umu.se
marie.wiberg@stat.umu.se
von Davier, A.A., Holland, P.W., Thayer, D.T. (2004). The Kernel Method of Test Equating. Springer-Verlag New York.
Holland, P.W., Thayer, D. (1998). Univariate and Bivariate Loglinear Models for Discrete Test Score Distributions ETS Technical Report No 98-1.
kequate
PREp
freqdata<-data.frame(X=c(1,2,2,1,2,2,2,2,3,1,2,1,4,2,1,1,3,3,3,3), A=(c(0,2,1,1,0,3,1,2,2,0,2,0,3,1,1,2,2,2,1,2))) Pdata<-kefreq(freqdata$X, 0:5, freqdata$A, 0:3) Pglm<-glm(frequency~X+I(X^2)+A+I(A^2)+X:A, data=Pdata, family="poisson", x=TRUE) Pobs<-matrix(Pdata$freq, nrow=6)/sum(Pglm$y) Pest<-matrix(Pglm$fitted.values, nrow=6)/sum(Pglm$y) cdP<-cdist(Pest, Pobs, 0:5, 0:3) plot(cdP)
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