mnl_diversion_ratios_parallel: Compute MNL diversion ratios (parallelized over individuals)

In choicer: Discrete Choice Models for Economic Applications

Compute MNL diversion ratios (parallelized over individuals)

Description

Computes the diversion ratio matrix DR(j->k), which measures the fraction of demand lost by alternative j that is captured by alternative k. For MNL: DR(j->k) = sum_n(w_n * P_nj * P_nk) / sum_n(w_n * P_nj * (1 - P_nj))

Usage

mnl_diversion_ratios_parallel(
  theta,
  X,
  alt_idx,
  M,
  weights,
  use_asc = TRUE,
  include_outside_option = FALSE
)

Arguments

theta	K + J - 1 or K + J vector with model parameters
X	sum(M) x K design matrix with covariates.
alt_idx	sum(M) x 1 vector with indices of alternatives; 1-based indexing
M	N x 1 vector with number of alternatives for each individual
weights	N x 1 vector with weights for each observation
use_asc	whether to use alternative-specific constants
include_outside_option	whether to include outside option

Value

J x J matrix where entry (k, j) = DR(j->k). Diagonal is 0.

Examples

library(data.table)
set.seed(42)
N <- 50; J <- 3
dt <- data.table(id = rep(1:N, each = J), alt = rep(1:J, N))
dt[, `:=`(x1 = rnorm(.N), x2 = rnorm(.N))]
dt[, choice := 0L]
dt[, choice := sample(c(1L, rep(0L, J - 1))), by = id]
fit <- run_mnlogit(dt, "id", "alt", "choice", c("x1", "x2"))
dr <- choicer:::mnl_diversion_ratios_parallel(coef(fit), fit$data$X, fit$data$alt_idx,
  fit$data$M, fit$data$weights)
dr

choicer documentation built on Sept. 5, 2026, 1:07 a.m.