Description Details Author(s) References Examples
Statistical interpretation of forensic glass transfer (Simulation of the probability distribution of recovered glass fragments).
Package: | tfer |
Type: | Package |
Version: | 1.1-1 |
Date: | 2015-02-24 |
License: | GPL-2 |
LazyLoad: | yes |
Depends: | methods |
The tfer
package provides functions for simulating the number of
recovered glass fragments given the conditions set by the user on
factors affecting the transfer, persistence and recovery of glass
fragments. A large simulation size will provide precise estimates of
transfer probabilities to be used in the Bayesian interpretation of
forensic glass evidence.
The transfer
constructor function creates an object of class
transfer
consisting of a list of simulated number of recovered
glass fragments and the input parameters set by the user. This function
is based on the full graphical model in Curran et al. (1998). The
user can specify arguments for simulation size, distance, transfer,
persistence and recovery properties.
The values
function extracts the simulated random variates from a
transfer
object. para
returns the input parameters and
user-specified arguments as a numeric vector. parameters
is an
alternative way of displaying the input parameters and arguments. The
initial information specified by the user are concatenated and displayed
as a string. Users may find this more informative than para
as it
displays what each parameter denotes.
tprob
returns the transfer probabilities for each
unique value of the simulated random variates. If the user is only
interested in the probabilities of recovering a certain number of
fragments, this can be specified as the second argument of tprob
.
summary
provides summary statistics of transfer
objects
and returns a list of input parameters, five-number summary and
probabilities of transfer.
The user has three plotting options for producing a graphical view of a
transfer
object. The plot type can be specified as (0 = barplot
of probabilities, 1 = barplot of frequencies or 2 = histogram).
A barplot of probabilities is set as the default.
James Curran and TingYu Huang
Maintainer: TingYu Huang <thua041@aucklanduni.ac.nz>
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.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 | 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 transfer probabilities (default)
plot(y, ptype = 0)
plot(y)
## barplot of transfer frequencies
plot(y, ptype = 1)
## histogram
plot(y, ptype = 2)
|
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