Backtest one or more diseasenowcasting models

backtest() translates native model() specifications into labelled tbl.now::engine_diseasenowcasting() specifications and delegates the full retrospective workflow to tbl.now::nowcast_backtest(). The returned object is therefore the common nowcast_backtest result used by tbl.now for tidying, forecast conversion, scoring, weighting, and ensembling.

Usage

backtest(
  data,
  models = diseasenowcasting::model(),
  dates = NULL,
  type = c("two_stage", "one_stage", "auto"),
  horizon = NULL,
  n_dates = 4L,
  n_draws = 1000L,
  K = 25L,
  np_spread = 1,
  seed = NULL,
  keep_draws = FALSE,
  on_error = c("warn", "abort"),
  verbose = TRUE,
  truth_axis = NULL,
  truth_type = NULL,
  quantile_levels = tbl.now::nowcast_quantile_levels(),
  ...
)

Arguments

data: A tbl.now::tbl_now holding the full data, including observations that arrived after the retrospective nowcast dates.
models: A model() or list of models. Names on the list become the canonical method labels; unnamed models receive labels from their component names. Labels must be unique.
dates: Retrospective nowcast origins, passed as now_dates to tbl.now::nowcast_backtest().
type: "two_stage", "one_stage", or "auto", passed to every diseasenowcasting engine.
horizon: Number of time units of hindsight used by tbl.now when dates = NULL. NULL uses 4 for ordinary data and the largest model settlement horizon for count-cumulative data (26 for its automatic model).
n_dates: Number of automatic retrospective origins. Ignored when dates is supplied. Default 4.
n_draws: Posterior draws per fit.
K, np_spread: Native two-stage fitting controls passed to every engine.
seed: Optional base seed. tbl.now derives a stable seed for each model/date fit from this value.
keep_draws: Whether the canonical backtest retains posterior draws.
on_error: Either "warn" to record and skip failed cells or "abort".
verbose: Whether to report progress.
truth_axis, truth_type: Canonical scoring truth controls passed to tbl.now::nowcast_backtest(). When both are NULL, they follow the native estimand: reported totals without a revision process, confirmed cases for confirmation/both modes, and still-standing cases for retraction-only mode.
quantile_levels: Quantile probabilities requested from every model.
...: Additional arguments passed to every nowcast() fit through its engine specification.

Value

A tbl.now::nowcast_backtest object.

Usage

Arguments

Value

See also