bellreg
Count Regression Models Based on the Bell Distribution
Bell regression models for count data with overdispersion. The implemented models account for ordinary and zero-inflated regression models under both frequentist and Bayesian approaches. Theoretical details regarding the models implemented in the package can be found in Castellares et al. (2018)
bellreg
The goal of bellreg is to provide a set of functions to fit regression models for count data with overdispersion using the Bell distribution. The implemented models account for ordinary and zero-inflated regression models under both frequentist and Bayesian approaches. Theoretical details regarding the models implemented in the package can be found in Castellares et al. (2018) doi:10.1016/j.apm.2017.12.014 and Lemonte et al. (2020) doi:10.1080/02664763.2019.1636940.
Installation
You can install the development version of bellreg from GitHub with:
# install.packages("devtools")
devtools::install_github("fndemarqui/bellreg")
Example
library(bellreg)
data(faults)
# ML approach:
mle <- bellreg(nf ~ lroll, data = faults, approach = "mle", init = 0)
summary(mle)
#> Call:
#> bellreg(formula = nf ~ lroll, data = faults, approach = "mle",
#> init = 0)
#>
#> Coefficients:
#> Estimate StdErr z.value p.value
#> (Intercept) 0.98524220 0.33219474 2.9659 0.003018 **
#> lroll 0.00190934 0.00049004 3.8963 9.766e-05 ***
#> ---
#> Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
#>
#> logLik = -88.96139 AIC = 181.9228
# Bayesian approach:
bayes <- bellreg(nf ~ lroll, data = faults, approach = "bayes", refresh = FALSE)
summary(bayes)
#>
#> bellreg(formula = nf ~ lroll, data = faults, approach = "bayes",
#> refresh = FALSE)
#>
#> mean se_mean sd 2.5% 25% 50% 75% 97.5% n_eff Rhat
#> (Intercept) 0.984 0.007 0.334 0.331 0.758 0.978 1.213 1.627 2222.313 1.001
#> lroll 0.002 0.000 0.000 0.001 0.002 0.002 0.002 0.003 2478.992 1.001
#>
#> Inference for Stan model: bellreg.
#> 4 chains, each with iter=2000; warmup=1000; thin=1;
#> post-warmup draws per chain=1000, total post-warmup draws=4000.