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Find Quantile for Target Subgroup Proportion

Source: R/find_k_inter_main.R
find_quantile_for_proportion.Rd

Determines the quantile cutpoint that achieves a target proportion of observations in a subgroup. Useful for calibrating subgroup sizes.

Usage

find_quantile_for_proportion(
  data,
  var_name,
  target_prop,
  direction = "less",
  tol = 1e-04
)

Arguments

data

A data.frame containing the variable of interest

var_name

Character string specifying the variable name to analyze

target_prop

Numeric value between 0 and 1 specifying the target proportion of observations to be included in the subgroup

direction

Character string: "less" for values <= cutpoint (default), "greater" for values > cutpoint

tol

Numeric tolerance for root finding algorithm. Default is 0.0001

Value

A list containing:

quantile

The quantile value (between 0 and 1) that achieves the target proportion

cutpoint

The actual data value corresponding to this quantile

actual_proportion

The achieved proportion (should equal target_prop within tolerance)

Details

This function uses root finding (uniroot) to determine the quantile that results in exactly the target proportion of observations being classified into the subgroup. This is particularly useful when you want to ensure a specific subgroup size regardless of the data distribution.

See also

generate_aft_dgm_flex

Examples

if (FALSE) { # \dontrun{
gbsg <- survival::gbsg
# Find ER cutpoint for 12.5% subgroup
result <- find_quantile_for_proportion(
  data = gbsg,
  var_name = "er",
  target_prop = 0.125,
  direction = "less"
)

print(result)
# Use in subgroup definition
subgroup_cuts = list(
  er = list(type = "quantile", value = result$quantile)
)
} # }