permutation_brier: permutation_brier
In rzgross/uRbanmatching:

For a given match, computes the brier score distribution, assuming the pairings were truly random.

permutation_brier(
  x_mat,
  match_list,
  design = "cross_all",
  use_cv = TRUE,
  num_permutations = 100L,
  match_predict_function = match_predict_xgb(),
  num_folds = 5,
  train_fraction = 0.7
)

`x_mat`	Typical input matrix
`match_list`	Match result
`design`	See `predict_prepare`
`use_cv`	Logical, default TRUE: wether to use CV to get briers? Else split.
`num_permutations`	Number of permutations to do.
`match_predict_function`	Function to predict treated units.
`num_folds`	If using CV, how many folds to make.
`train_fraction`	If using split, what fraction to train.