transfer: Glass Transfer, Persistence and Recovery Probabilities

In jmcurran/tfer: Forensic Glass Transfer Probabilities

Description

Simulate the number of glass fragments recovered given the conditions set by the user.

Usage

transfer(N = 10000, d = 0.5, deffect = 1, lambda = 120, Q = 0.05, l0 =
0.8, u0 = 0.9, lstar0 = 0.1, ustar0 = 0.15, lj = 0.45, uj = 0.7, lstarj
= 0.05, ustarj = 0.1, lR = 0.5, uR = 0.7, t = 1.5, r = 0.5)

Arguments

N	Simulation size
d	The breaker's distance from the window
deffect	Distance effect. deffect = 1 when distance effect exists. Otherwise deffect = 0.
lambda	The average number of glass fragments transferred to the breaker's clothing.
Q	Proportion of high persistence fragments.
l0	Lower bound on the percentage of fragments lost in the first hour
u0	Upper bound on the percentage of fragments lost in the first hour
lstar0	Lower bound on the percentage of high persistence fragments lost in the first hour
ustar0	Upper bound on the percentage of high persistence fragments lost in the first hour
lj	Lower bound on the percentage of fragments lost in the j'th hour
uj	Upper bound on the percentage of fragments lost in the j'th hour
lstarj	Lower bound on the percentage of high persistence fragments lost in the j'th hour
ustarj	Upper bound on the percentage of high persistence fragments lost in the j'th hour
lR	Lower bound on the percentage of fragments expected to be detected in the lab
uR	Upper bound on the percentage of fragments expected to be detected in the lab
t	Time between commission of crime and apprehension of suspect
r	Probability r in ti ~ NegBinom(t, r)

Value

Y	The simulated values of recovered glass fragments
para	Input parameters

Author(s)

James Curran and TingYu Huang

References

Curran, J. M., Hicks, T. N. & Buckleton, J. S. (2000). Forensic interpretation of glass evidence. Boca Raton, FL: CRC Press.

Curran, J. M., Triggs, C. M., Buckleton, J. S., Walsh, K. A. J. & Hicks T. N. (January, 1998). Assessing transfer probabilities in a Bayesian interpretation of forensic glass evidence. Science & Justice, 38(1), 15-21.

Examples

library(tfer)

## create a transfer object using default arguments
y = transfer()

## probability table
probs = tprob(y)

## extract the probabilities of recovering 8 to 15
## glass fragments given the user-specified arguments
tprob(y, 8:15) 

## produce a summary table for a transfer object
summary(y)

## barplot of probabilities (default)
plot(y, ptype = 0)
plot(y)

## barplot of transfer frequencies
plot(y, ptype = 1)

## histogram
plot(y, ptype = 2)

jmcurran/tfer documentation built on May 19, 2019, 1:53 p.m.