pumBayes (version 1.0.2)

predict_irt: Calculate Probabilities for Dynamic Item Response Theory Model

Description

This function computes the probability matrix for a dynamic item response theory (IRT) model. Specifically, it calculates the probabilities of voting "Yea" for each legislator (member), issue, and time period based on the posterior samples of model parameters.

Usage

predict_irt(vote_info, years_v, post_samples)

Value

An array of probabilities with three dimensions. The first one represents to members, the second one refers to issues, and the third one refers to MCMC iterations.

Arguments

vote_info

A logical vote matrix where rows represent members and columns represent issues. The entries should be FALSE ("No"), TRUE ("Yes"), or NA (missing data).

years_v

A vector representing the time period for each vote in the model.

post_samples

MCMC results obtained from `wnominate' function in `wnominate' package.

Examples

# \donttest{
# Long-running example
data(scotus.1937.2021)
library(MCMCpack)
special_judge_ind = sapply(c("HLBlack", "PStewart", "WHRehnquist"),
                           function(name){grep(name, rownames(mqVotes))})
e0_v = rep(0, nrow(mqVotes))
E0_v = rep(1, nrow(mqVotes))
e0_v[special_judge_ind] = c(-2, 1, 3)
E0_v[special_judge_ind] = c(10, 10, 10)
theta.start = rep(0, nrow(mqVotes))
indices = c(2, 5, 8, 9, 12, 22, 23, 24, 25, 29, 30, 33, 36, 39,
            42, 43, 44)
values = c(1, 1, -1, -2, -2, 1, -1, 1, 1, -1, 1, 3, 3, 3, 1, 1, -1)
theta.start[indices] = values
data(scotus.1937.2021)
scotus.MQ = MCMCdynamicIRT1d(mqVotes, mqTime, mcmc = 2,
                             burnin = 0, thin = 1, tau2.start = 0.1,
                             theta.start = theta.start, a0 = 0, A0 = 1, b0 = 0, B0 = 1, c0 = -10,
                             d0 = -2, e0 = e0_v, E0 = E0_v,
                             theta.constraints=list(CThomas = "+", SAAlito = "+", WJBrennan = "-",
                                                    WODouglas = "-", CEWhittaker = "+"))
scotus.MQ.predprob = predict_irt(mqVotes, mqTime, scotus.MQ)
# }