Estimate Barton & Lord’s (1981) https://doi.org/10.1002/j.2333-8504.1981.tb01255.x four parameter IRT model with lower and upper asymptotes using Bayesian formulation described by Culpepper (2016) https://doi.org/10.1007/s11336-015-9477-6.

You can install fourPNO from CRAN using:

install.packages("fourPNO")

Or, you can be on the cutting-edge development version on GitHub using:

if(!requireNamespace("devtools")) install.packages("devtools")
devtools::install_github("tmsalab/fourPNO")

To use the fourPNO package, load it into R using:

library("fourPNO")

Inside the package, the estimation routines can be viewed as:

• Gibbs_2PNO()
• Gibbs_4PNO()

Steven Andrew Culpepper

To ensure future development of the package, please cite fourPNO package if used during an analysis or simulation study. Citation information for the package may be acquired by using in R:

citation("fourPNO")

GPL (>= 2)