Compute bias relative to term-specific true values within grouped simulation results

Computes the mean bias (difference between estimated values and true values) within each group, typically inside evaluate_model_results() for simulation evaluation pipelines.

Usage

eval_bias(x, term = NULL, na.rm = FALSE)

Arguments

x

A numeric vector of estimates (e.g., from a model term).

term

A named numeric vector providing the true value for each term. For example, c("(Intercept)" = 0, x = 2) to specify the true values for each term. If NULL (default), bias is computed relative to zero.

na.rm

Logical; whether to remove missing values when computing the mean bias. Defaults to FALSE.

Value

A numeric scalar representing the mean bias within the current group.

Details

This function is designed to be used inside dplyr::summarise() within a grouped tidyverse pipeline, typically after grouping by term. It computes the mean of x minus the true value for the corresponding term.

If term is provided, the current grouping must include a term variable matching the names in term. If a term in the group is not found in the provided term mapping, the function will return NA with a warning.

Examples

library(dplyr)
#> Error in library(dplyr): there is no package called ‘dplyr’
library(purrr)
library(broom.mixed)
#> Error in library(broom.mixed): there is no package called ‘broom.mixed’

# Simulate and fit models
sim_models <- tibble(
  id = 1:50,
  model = map(1:50, ~ lm(mpg ~ wt, data = mtcars))
) |>
  extract_model_results()
#> Error in loadNamespace(x): there is no package called ‘tidyr’

# Compute bias relative to true value (hypothetical slope = -5)
sim_models |>
  filter(term == "wt") |>
  evaluate_model_results(
    bias = eval_bias(
      estimate,
      term = c("wt" = -5)
    )
  )
#> Error in loadNamespace(x): there is no package called ‘dplyr’

# Compute bias relative to zero for all terms
sim_models |>
  group_by(term) |>
  evaluate_model_results(
    bias = eval_bias(estimate)
  )
#> Error in loadNamespace(x): there is no package called ‘dplyr’