Apply the delay to generate a point nowcast Generate a point estimate of a completed reporting square (or rectangle) from a reporting triangle that we want to complete with a nowcast and a delay PMF. Each element is computed by taking the product of the expected number of total cases assigned to a reference time $t$ and the proportion of those cases reported on delay $d$. The formula to obtain the expected number of total cases as a function of the reporting delay and previous observations was derived elsewhere. This code was adapted from code written (under an MIT license) by the Karlsruhe Institute of Technology RESPINOW German Hospitalization Nowcasting Hub. Modified from: https://github.com/KITmetricslab/RESPINOW-Hub/blob/7cce3ae2728116e8c8cc0e4ab29074462c24650e/code/baseline/functions.R#L55 #nolint

Source: R/apply_delay.R

apply_delay.Rd

Usage

apply_delay(rep_tri_to_nowcast, delay_pmf)

Arguments

rep_tri_to_nowcast: Matrix of the reporting triangle to be nowcasted, with rows representing the time points of reference and columns representing the delays
delay_pmf: Vector of delays assumed to be indexed starting at the first delay column in rep_mat_to_nowcast

Value

point_nowcast_matrix Matrix of the same number of rows and columns as the rep_mat_to_nowcast but with the missing values filled in as point estimates

Examples

triangle <- matrix(
  c(
    80, 50, 25, 10,
    100, 50, 30, 20,
    90, 45, 25, NA,
    80, 40, NA, NA,
    70, NA, NA, NA
  ),
  nrow = 5,
  byrow = TRUE
)
delay_pmf <- get_delay_estimate(
  reporting_triangle = triangle,
  max_delay = 3,
  n = 4
)
point_nowcast_matrix <- apply_delay(
  rep_tri_to_nowcast = triangle,
  delay_pmf = delay_pmf
)
print(point_nowcast_matrix)
#>      [,1]     [,2]     [,3]     [,4]
#> [1,]   80 50.00000 25.00000 10.00000
#> [2,]  100 50.00000 30.00000 20.00000
#> [3,]   90 45.00000 25.00000 17.78889
#> [4,]   80 40.00000 23.20529 15.92281
#> [5,]   70 35.24853 20.35851 13.96745