plot_lr_distribution: Plot Likelihood Ratio Distributions

In mispitools: Missing Person Identification Tools

Plot Likelihood Ratio Distributions

Description

Creates a density plot showing the expected log10(LR) distributions under both hypotheses:

• H1 (Related/Blue): Distribution when POI is the missing person

• H2 (Unrelated/Red): Distribution when POI is unrelated

This visualization helps assess the discriminatory power of the evidence and identify potential overlap between the two hypotheses.

Usage

plot_lr_distribution(datasim)

Arguments

datasim

A data.frame with columns Related and Unrelated containing LR values. Can be output from sim_lr_genetic, sim_lr_prelim, lr_to_dataframe, or lr_combine.

Details

If the input is a list (output from sim_lr_genetic), it is automatically converted to a data.frame using lr_to_dataframe.

The x-axis shows log10(LR), which is more interpretable than raw LR values:

• log10(LR) = 0 means LR = 1 (neutral evidence)

• log10(LR) > 0 means evidence favors H1 (related)

• log10(LR) < 0 means evidence favors H2 (unrelated)

Less overlap between distributions indicates better discrimination.

Value

A ggplot2 object showing overlaid density curves. Blue area represents H1 (Related), red area represents H2 (Unrelated).

References

Marsico FL, Vigeland MD, Egeland T, Herrera Pinero F (2021). "Making decisions in missing person identification cases with low statistical power." Forensic Science International: Genetics, 52, 102519. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1016/j.fsigen.2021.102519")}

See Also

plot_decision_curve for FPR/FNR trade-off visualization, decision_threshold for computing optimal thresholds, sim_lr_genetic, sim_lr_prelim for generating input.

Examples

# Using preliminary data
lr_sims <- sim_lr_prelim("sex", numsims = 500, seed = 123)
plot_lr_distribution(lr_sims)

# Using genetic data
library(forrel)
x <- linearPed(2)
x <- setMarkers(x, locusAttributes = NorwegianFrequencies[1:5])
x <- profileSim(x, N = 1, ids = 2)
lr_genetic <- sim_lr_genetic(x, missing = 5, numsims = 50, seed = 123)
plot_lr_distribution(lr_genetic)

mispitools documentation built on Aug. 26, 2026, 1:08 a.m.