Highest point of a log-likelihood surface

The maximum likelihood estimates of discrimination and difficulty on the grid of a surface from loglik_surface().

Usage

surface_maximum(loglik, a = attr(loglik, "a"), b = attr(loglik, "b"))

Arguments

loglik

Matrix of log-likelihoods, one row for each value of a and one column for each value of b.

a, b

The grids of discriminations and difficulties of the surface; by default those that loglik_surface() keeps with it.

Value

A list with a, b and loglik, the discrimination, difficulty and log-likelihood at the highest point; at a tie, the first in column order.

Examples

set.seed(1)
theta <- seq(-3, 3, length.out = 50)
surface <- loglik_surface(simulate_responses(theta, a = 1, b = -0.5), theta)
surface_maximum(surface)
#> $a
#> [1] 1.2
#> 
#> $b
#> [1] -1.3
#> 
#> $loglik
#> [1] -18.46392
#>