sens_spec_roc: Make ROC from sensitivity and specificity

In HopkinsIDD/phylosamp: Sample Size Calculations for Molecular and Phylogenetic Studies

Make ROC from sensitivity and specificity

Description

This is a wrapper function that takes output from the sens_spec_calc() function and constructs values for the Receiver Operating Characteristic (ROC) curve

Usage

sens_spec_roc(
  cutoff,
  mut_rate,
  mean_gens_pdf,
  max_link_gens = 1,
  max_gens = NULL,
  max_dist = NULL
)

Arguments

cutoff	the maximum genetic distance at which to consider cases linked
mut_rate	mean number of mutations per generation, assumed to be Poisson distributed
mean_gens_pdf	the density distribution of the mean number of generations between cases; the index of this vector is assumed to be the discrete distance between cases
max_link_gens	the maximum generations of separation for linked pairs
max_gens	the maximum number of generations to consider, if NULL (default) value set to the highest number of generations in mean_gens_pdf with a non-zero probability
max_dist	the maximum distance to calculate, if NULL (default) value set to max_gens * 99.9th percentile of mut_rate Poisson distribution

Value

data frame with cutoff, sensitivity, and 1-specificity

Author(s)

Shirlee Wohl and Justin Lessler

See Also

Other mutrate_functions: gen_dists(), get_optim_roc(), sens_spec_calc()

Examples

# ebola-like pathogen
R <- 1.5
mut_rate <- 1

# use simulated generation distributions
data('genDistSim')
mean_gens_pdf <- as.numeric(genDistSim[genDistSim$R == R, -(1:2)])

# get theoretical genetic distance dist based on mutation rate and generation parameters
dists <- as.data.frame(gen_dists(mut_rate = mut_rate,
                                 mean_gens_pdf = mean_gens_pdf,
                                 max_link_gens = 1))

dists <- reshape2::melt(dists,
                        id.vars = 'dist',
                        variable.name = 'status',
                        value.name = 'prob')

# get sensitivity and specificity using the same paramters
roc_calc <- sens_spec_roc(cutoff = 1:(max(dists$dist)-1),
                          mut_rate = mut_rate,
                          mean_gens_pdf = mean_gens_pdf)

HopkinsIDD/phylosamp documentation built on May 28, 2023, 3:21 a.m.