Type: | Package |
Title: | Forensic Glass Transfer Probabilities |
Version: | 1.3 |
Date: | 2020-07-14 |
Author: | James Curran and TingYu Huang |
Maintainer: | James Curran <j.curran@auckland.ac.nz> |
Description: | Statistical interpretation of forensic glass transfer (Simulation of the probability distribution of recovered glass fragments). |
License: | GPL-2 |
LazyLoad: | yes |
Encoding: | UTF-8 |
RoxygenNote: | 7.1.1 |
NeedsCompilation: | no |
Packaged: | 2020-07-13 21:44:11 UTC; jcur002 |
Repository: | CRAN |
Date/Publication: | 2020-07-15 09:40:02 UTC |
Extract Transfer and Persistence Parameters I
Description
Displays input parameters and arguments passed to transfer
.
Usage
getParams(tferObj)
Arguments
tferObj |
An object of class |
Details
getParams
is one of the two accessor functions for a transfer
object.
Value
getParams
returns a list of input parameters and their corresponding values.
Author(s)
TingYu Huang
See Also
Examples
library(tfer)
y = transfer()
getParams(y)
Extract Transfer Values
n
getValues
is a accessor function which returns the number of recovered
glass fragments generated by transfer
.
Description
Extract Transfer Values
n
getValues
is a accessor function which returns the number of recovered
glass fragments generated by transfer
.
Usage
getValues(tferObj)
Arguments
tferObj |
An object of class |
Value
values
returns a numeric vector of random variates.
Author(s)
TingYu Huang and James Curran
See Also
Examples
library(tfer)
y = transfer()
getValues(y)
plot method for objects of transfer class
Description
plot method for objects of transfer class
Usage
## S3 method for class 'tfer'
plot(
x,
ptype = c("density", "freq", "hist"),
xlab = "n",
main = "",
col = "red",
...
)
Arguments
x |
an object of class |
ptype |
one of |
xlab |
the x-axis label, by default "n" |
main |
the plot title, empty by default |
col |
the colour of the bars in the plot, by default "red" |
... |
any other arguments to be passed to |
print
method for transfer objects
Description
Prints a summary of the simulation input parameters
Usage
## S3 method for class 'transfer'
print(x, ...)
Arguments
x |
an object of class transfer |
... |
included for consistency but not used |
summary
method for transfer objects
Description
Prints a summary of the simulation input parameters
Usage
## S3 method for class 'transfer'
summary(object, ...)
Arguments
object |
an object of class transfer |
... |
extra arguments passed to |
Value
A list
with three elements is returned invisibly:
- parameters
list containing all the simulation parameters
- values
a numeric vector of the simulated values
- probability
a named numeric vector giving the probability of recovering 0, 1, 2, ... fragments
Return a table of T probabilities for all observed values
Description
Return a table of T probabilities for all observed values
Usage
tprob(tferObj, x)
Arguments
tferObj |
an object of class |
x |
an optional set of values which specify the desired T-terms. E.g. x = c(0,1,2) would return T0, T1, and T2 and so on. Negative values of x will cause the function to stop. Values of x which exceed those observed will be assigned a value of zero. The return values will be returned in ascending order regardless of the order of x (although I suppose I could preserve the order if someone really cares). |
Value
A table of T probabilities, giving the probability that x fragments were recovered given they were transferred and persisted according to the other inputs of the model.
Examples
set.seed(123)
y = transfer()
tprob(y)
tprob(y, 55:120) ## max observed value is 113
Glass Transfer, Persistence and Recovery Probabilities
Description
Construct a transfer object to simulate the number of glass fragments recovered given the conditions set by the user.
Usage
transfer(
N = 10000,
d = 0.5,
deffect = TRUE,
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,
lt = 1,
ut = 2,
r = 0.5,
timeDist = c("negbin", "cnegbin", "uniform"),
loop = FALSE
)
Arguments
N |
Simulation size |
d |
The breaker's distance from the window |
deffect |
Distance effect. |
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 |
lt |
Lower bound on time between commission of crime and apprehension of suspect |
ut |
Upper bound on time between commission of crime and apprehension of suspect |
r |
Probability r in ti ~ NegBinom(t, r) |
timeDist |
the distribution for the random amount of time between the commission of
the crime and the apprehension of the suspect. There are three choices |
loop |
if |
Value
a list
containing:
- results
The simulated values of recovered glass fragments
- paramList
Input parameters
The returned object has S3 class types tfer and transfer for backwards compatibility
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)
plot(y)
## barplot of transfer frequencies
plot(y, ptype = "f")
## histogram
plot(y, ptype = "h")