conogive 
An R package for the congeneric ogive model.
Overview
The congeneric ogive model is a psychometric model for Likert scale data with one latent factor. This package has functions to estimate such models, calculate their ordinal reliabilities, and make predictions.
Installation
From inside R, use one of the following commands:
devtools::install_github("JonasMoss/conogive")Usage
Estimate a congeneric ogive model with congive, predict the value of
the latent factor with predict, and calculate the reliability with
ordinal_omega.
library("conogive")
extraversion = psychTools::bfi[c("E1", "E2", "E3", "E4", "E5")]
extraversion[, "E1"] = 7 - extraversion[, "E1"] # Reverse-coded item.
extraversion[, "E2"] = 7 - extraversion[, "E2"] # Reverse-coded item.
object = conogive(extraversion)
ordinal_omega(object) # Observed reliability
#> [1] 0.7046056
omega(object) # Theoretical reliability
#> [1] 0.8122608
hist(predict(object, extraversion)) # Plot distribution of predictions.
