Select the PP futility threshold minimising null expected sample size

Among candidate thresholds for which the one-sided 95\ confidence bound on power (power_LCB from summarize_grid_by_kappa) is at least the floor under every alternative scenario, selects the one with the smallest expected sample size under the null scenario. A threshold with an NA lower bound in any alternative scenario is infeasible. Ties in null expected sample size (within 1e-8) are broken in favour of the larger kappa.

Usage

select_kappa_star(
  summary_by_scenario,
  power_floor,
  null_scenario,
  alt_scenarios
)

Arguments

summary_by_scenario

A named list of data frames, one per scenario, each as returned by summarize_grid_by_kappa over the same kappa_grid.

power_floor

Minimum acceptable lower confidence bound on power: a scalar applied to every alternative scenario, or a named numeric vector with one entry per alternative scenario (e.g. from compute_relative_floors).

null_scenario

Name of the null scenario in summary_by_scenario.

alt_scenarios

Character vector of alternative scenario names.

Value

A list with kappa_star (the selected threshold, or NA with a warning if none is feasible) and feasibility_table (kappa, null_ESS, feasible and, per alternative scenario, power_<s>, power_LCB_<s> and floor_<s>).

See also

summarize_grid_by_kappa, compute_relative_floors