BLP contraction mapping for multinomial logit model

Usage

# S3 method for class 'choicer_mnl'
blp(
  object,
  target_shares,
  delta_init = NULL,
  tol = 1e-08,
  max_iter = 1000,
  ...
)

Arguments

object: A choicer_mnl object fitted with keep_data = TRUE.
target_shares: Numeric vector of target market shares. Length J_inside when no outside option, or J_inside + 1 (with the outside option's share at index 1) when include_outside_option = TRUE.
delta_init: Initial guess for delta (ASC) values. If NULL, uses the estimated ASCs from the fitted model.
tol: Convergence tolerance (default 1e-8).
max_iter: Maximum iterations (default 1000).
...: Additional arguments (ignored).

Value

Converged delta (ASC) vector.

Examples

# \donttest{
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))]
#>         id   alt         x1          x2
#>      <int> <int>      <num>       <num>
#>   1:     1     1  1.3709584 -0.04069848
#>   2:     1     2 -0.5646982 -1.55154482
#>   3:     1     3  0.3631284  1.16716955
#>   4:     2     1  0.6328626 -0.27364570
#>   5:     2     2  0.4042683 -0.46784532
#>  ---                                   
#> 146:    49     2  1.1133860 -0.47733551
#> 147:    49     3 -0.4809928 -0.16626149
#> 148:    50     1 -0.4331690  0.86256338
#> 149:    50     2  0.6968626  0.09734049
#> 150:    50     3 -1.0563684 -1.62561674
dt[, choice := 0L]
#>         id   alt         x1          x2 choice
#>      <int> <int>      <num>       <num>  <int>
#>   1:     1     1  1.3709584 -0.04069848      0
#>   2:     1     2 -0.5646982 -1.55154482      0
#>   3:     1     3  0.3631284  1.16716955      0
#>   4:     2     1  0.6328626 -0.27364570      0
#>   5:     2     2  0.4042683 -0.46784532      0
#>  ---                                          
#> 146:    49     2  1.1133860 -0.47733551      0
#> 147:    49     3 -0.4809928 -0.16626149      0
#> 148:    50     1 -0.4331690  0.86256338      0
#> 149:    50     2  0.6968626  0.09734049      0
#> 150:    50     3 -1.0563684 -1.62561674      0
dt[, choice := sample(c(1L, rep(0L, J - 1))), by = id]
#>         id   alt         x1          x2 choice
#>      <int> <int>      <num>       <num>  <int>
#>   1:     1     1  1.3709584 -0.04069848      0
#>   2:     1     2 -0.5646982 -1.55154482      0
#>   3:     1     3  0.3631284  1.16716955      1
#>   4:     2     1  0.6328626 -0.27364570      0
#>   5:     2     2  0.4042683 -0.46784532      0
#>  ---                                          
#> 146:    49     2  1.1133860 -0.47733551      0
#> 147:    49     3 -0.4809928 -0.16626149      0
#> 148:    50     1 -0.4331690  0.86256338      1
#> 149:    50     2  0.6968626  0.09734049      0
#> 150:    50     3 -1.0563684 -1.62561674      0
fit <- run_mnlogit(dt, "id", "alt", "choice", c("x1", "x2"))
#> Optimization run time 0h:0m:0s
blp(fit, target_shares = rep(1/J, J))
#>             [,1]
#> [1,]  0.00000000
#> [2,] -0.03013133
#> [3,]  0.01204404
# }