H23 Calculate the rate locally

Use your current course session. Preparation and course runner · R script ↓

H23 Calculate the rate locally

Goal: Reproduce the hand calculation.

Prerequisites: H22.

A successful in-memory run supports exploratory measurement, but not an approved frozen report.

training_step(
  "H23",
  {
    local_rate <- dataraft.metrics::dr_measure(
      cohort_run,
      cancellation_metric,
      by = character()
    )
    print(local_rate)
    stopifnot(isTRUE(all.equal(local_rate$value, 1 / 6)))
  },
  needs = c("H22")
)

Expected result: A ratio of 0.1666667, or about 16.67 percent.

Task: Why not multiply by 100 in the definition?

H23a Handle an empty opening population

Goal: Prevent a rate without a valid denominator.

Prerequisites: H21; do not collect a metric from a blocked run.

A population with no eligible policies cannot support this rate. Run the counterexample, then return to cohort_run.

training_step(
  "H23a",
  {
    no_opening_data <- dated_policies
    no_opening_data$start_date <- as.Date("2026-08-10")
    no_opening_run <- dr_run(
      cohort_product,
      data = no_opening_data,
      write = FALSE,
      stop_on_failure = FALSE
    )
    print(dr_quality_report(no_opening_run))
    stopifnot(no_opening_run$status == "blocked")
  },
  needs = c("H21")
)

Expected result: nonempty_denominator blocks output.

Task: Why would zero be misleading?