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Nowcast a reporting triangle from the delay pattern of settled weeks

Source: R/v4_nowcast_ecdf.R
nowcast_ecdf_v4.Rd

Completes each incomplete reference week from a pool of settled reference weeks. Each draw is the count observed so far, times a quantile of the completion ratios that the pool shows at the same delay day.

Usage

nowcast_ecdf_v4(
  x,
  max_delay_days,
  seed,
  n_sim = 1000,
  denominator_col = NULL,
  delay_window = 26
)

Arguments

x

The csfmt_reporting_triangle_v4 to nowcast.

max_delay_days

The delay horizon in days, delay day 0 to max_delay_days - 1. The nowcast estimates the count reported within it.

seed

The seed of the draws, one whole number.

n_sim

The number of draws.

denominator_col

A denominator column to nowcast on the same draws. Its observed total goes to $data as <denominator_col>_observed.

delay_window

The span, in weeks, of the settled weeks in the pool. NULL uses every settled week.

Value

A csfmt_ensemble_v4 with one row per reference week. $draws holds one matrix with n_sim columns per measure, named by the measure. $data holds original, the observed total, which includes every report at delay max_delay_days or later.

Details

The method is that of nowcast_delay_ecdf_v1(). With the same triangle and the same seed, the draws are identical. The draw matrix has the name of value_col, with no suffix. The function sets the seed itself and then restores the random-number state of the caller.

See also

Other v4 functions: as_ensemble_v4(), csfmt_ensemble_v4(), csfmt_reporting_triangle_v4(), ens_add_rate_v4(), ens_compress_v4(), mem_thresholds_v4(), nowcast_passthrough_v4(), print.csfmt_ensemble_v4(), short_term_trend_v4(), signal_detection_hlm_v4()

Examples

cal <- cstime::dates_by_isoyearweek
i <- match("2023-01", cal$isoyearweek)
set.seed(1)
monday <- as.Date(cal$mon[i + rep(0:39, each = 3)])
d <- data.table::data.table(
  isoyearweek_reference = cal$isoyearweek[i + rep(0:39, each = 3)],
  reporting_date = monday + rep(c(3, 10, 17), 40),
  numerator = rpois(120, c(30, 15, 5)),
  indicator_tag = "x", location_code = "nation", age = "total", sex = "total"
)
d <- d[reporting_date <= as.Date(cal$mon[i + 39]) + 6]
tri <- csfmt_reporting_triangle_v4(
  d,
  id_cols = c("indicator_tag", "location_code", "age", "sex")
)
ens <- nowcast_ecdf_v4(tri, max_delay_days = 21, seed = 4, n_sim = 200)
ens
#> <csfmt_ensemble_v4> full | 40 rows | 1 series | draws: numerator