Qval (version 1.2.3)

plot: Plot Methods for Various Qval Objects

Description

Generate visualizations for objects created by the Qval package. The generic `plot` dispatches to appropriate methods based on object class:

CDM

Barplot of attribute-pattern distribution (frequency and proportion).

sim.data

Barplot of simulated attribute-pattern distribution (frequency and proportion).

validation

Hull plot marking the suggested point in red (method = "Hull").

Usage

# S3 method for CDM
plot(x, ...)
# S3 method for sim.data
plot(x, ...)
# S3 method for validation
plot(x, i = 1, ...)

Value

None. Functions are called for side effects (plotting).

Arguments

x

An object of class CDM, sim.data, or validation.

...

Additional arguments (currently unused).

i

For validation objects, the index of the item for which to plot the Hull curve.

Methods (by class)

• plot(CDM): Plot method for CDM objects

• plot(sim.data): Plot method for sim.data objects

• plot(validation): Hull plot for validation objects

Examples

set.seed(123)
library(Qval)

# \donttest{
K <- 4
I <- 20
IQ <- list(
  P0 = runif(I, 0.2, 0.4),
  P1 = runif(I, 0.6, 0.8)
)

################################################################
# Example 1: sim.data object                                   #
################################################################
Q <- sim.Q(K, I)
data.obj <- sim.data(Q = Q, N = 500, IQ = IQ,
                     model = "GDINA", distribute = "horder")

plot(data.obj)
                     

################################################################
# Example 2: CDM object                                        #
################################################################
CDM.obj <- CDM(data.obj$dat, Q, model = "GDINA", 
               method = "EM", maxitr = 2000, verbose = 1)
plot(CDM.obj)


################################################################
# Example 3: validation object (Hull plot)                     #
################################################################
MQ <- sim.MQ(Q, 0.1)

CDM.obj <- CDM(data.obj$dat, MQ)

############### ESA ###############
Hull.obj <- validation(data.obj$dat, MQ, CDM.obj, 
                       method = "Hull", search.method = "ESA") 

## plot Hull curve for item 20
plot(Hull.obj, 20)

############### PAA ###############
Hull.obj <- validation(data.obj$dat, MQ, CDM.obj, 
                       method = "Hull", search.method = "PAA") 

## plot Hull curve for item 20
plot(Hull.obj, 20)
# }