Confidence bands

Description

Graphic bands of confidence of an item, to evaluate the goodness of fit of the model.

Usage

plotenvelope(item, numboot, alpha, model, data)

Arguments

Value

plot with the envelopes and the caracteristic curve of the item.

Author(s)

SICS Research, National University of Colombia ammontenegrod@unal.edu.co

References

David Thissen, Howard Wainer D. (1990). Confidence Envelopes for Item Response Theory. Journal of Educational Statistics, Vol 15, No 2, 113-128.

See Also

orlando_itemf, z3_itemf

Examples

#Simulates a test and returns a list:
test <- simulateTest()

#the simulated data:
t_data <- test$test

#model:
mod <- irtpp(dataset = t_data,model = "3PL")

#Envelopes:
item <- 8
numboot <- 100
alpha <- 0.05

#call the function:
plotenvelope(item=item,numboot=numboot,alpha=alpha,model=mod,data=t_data)

Results

R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

> library(IRTpp)
> png(filename="/home/ddbj/snapshot/RGM3/R_CC/result/IRTpp/plotevenlope.Rd_%03d_medium.png", width=480, height=480)
> ### Name: plotevenlope
> ### Title: Confidence bands
> ### Aliases: plotenvelope plotevenlope
> 
> ### ** Examples
> 
> 
> #Simulates a test and returns a list:
> test <- simulateTest()
> 
> #the simulated data:
> t_data <- test$test
> 
> #model:
> mod <- irtpp(dataset = t_data,model = "3PL")
> 
> #Envelopes:
> item <- 8
> numboot <- 100
> alpha <- 0.05
> 
> #call the function:
> plotenvelope(item=item,numboot=numboot,alpha=alpha,model=mod,data=t_data)
> 
> 
> 
> 
> 
> dev.off()
null device 
          1 
>