plot.pmatrix.class {mokken} | R Documentation |
S3 Method to plot
objects of class pmatrix.class.
Graphic display of the checks of pmatrix.
One graph for each item plotting the rows of the P(++) matrix and rows of the P(–) matrix.
If nonintersection holds the lines in the plots of the P(++) matrix must be nondecreasing
and the lines in the plots of the P(–) matrix nust be nonincreasing.
## S3 method for class 'pmatrix.class': plot(x, items = all, pmatrix="both", ...)
x |
Object of class pmatrix.class produced by check.pmatrix . |
items |
vector containing the numbers of the item pairs for which the results are depicted graphically. Default the results for all items are depicted. |
pmatrix |
Valid options are "ppp" , "pmm" , and "both" .
If pmatrix="ppp" , then the P(++) matrix is plotted,
if pmatrix="pmm" , then the P(–) matrix is plotted,
if pmatrix="both" , then both the P(++) matrix and P(–) matrix are plotted. |
... |
Optional graphical parameters will be ignored |
The default graphic device in R may only display the last graph.
In the plot of the P(++) matrix and the P(–) matrix, the x-axis contains the k =(J-1)m item steps not pertaining to item j in order of popularity (ascending). Let Y_g=1 indicate that the g-th item step has been taken: i.e. Xi >=q y and let Y_g=0 indicate that the g-th item step has not been taken: i.e. Xi < y. The m lines in the plot of the P(++) matrix connect P(X_j >=q x, Y_1=1), ..., P(X_j >=q x, Y_k=1)), x = 1, ... m. The m lines in the plot of the P(–) matrix connect P(X_j < x, Y_1=0), ..., P(X_j < x, Y_k=0)), x = 1, ..., m.
If the number of item steps on the x-axis is greater than 10, then the labels are not displayed,
Returns a graph.
L. A. van der Ark a.vdark@uvt.nl
Molenaar, I.W. and Sijtsma, K. (2000) User's Manual MSP5 for Windows [Software manual]. Groningen, The Netherlands: IEC ProGAMMA.
Sijtsma, K, and Molenaar, I. W. (2002) Introduction to nonparametric item response theory. Thousand Oaks, CA: Sage.
Van der Ark, L. A. (2007). Mokken scale analysis in R. Journal of Statistical Software. http://www.jstatsoft.org
check.pmatrix
, summary.pmatrix.class
data(acl) Communality <- acl[,1:10] pmatrix.list <- check.pmatrix(Communality) plot(pmatrix.list) summary(pmatrix.list)