bootcor {highriskzone} | R Documentation |
Bootstrap correction to obtain desired failure probability
Description
Simulation-based iterative procedure to correct for possible bias with respect to the failure probability alpha
Usage
bootcor(
ppdata,
cutoff,
numit = 1000,
tol = 0.02,
nxprob = 0.1,
intens = NULL,
covmatrix = NULL,
simulate = "intens",
radiusClust = NULL,
clustering = 5,
verbose = TRUE
)
Arguments
ppdata |
Observed spatial point process of class ppp. |
cutoff |
Desired failure probability alpha, which is the probability of having unobserved events outside the high-risk zone. |
numit |
Number of iterations to perform (per tested value for cutoff). Default value is 1000. |
tol |
Tolerance: acceptable difference between the desired failure probability and the fraction of high-risk zones not covering all events. Default value is 0.02. |
nxprob |
Probability of having unobserved events. Default value is 0.1. |
intens |
(optional) estimated intensity of the observed process (object of class "im",
see |
covmatrix |
(optional) Covariance matrix of the kernel of a normal distribution, only meaningful if no intensity is given. If not given, it will be estimated. |
simulate |
The type of simulation, can be one of |
radiusClust |
(optional) radius of the circles around the parent points in which the cluster
points are located. Only used for |
clustering |
a value >= 1 which describes the amount of clustering; the
adjusted estimated intensity of the observed pattern is divided by
this value; it also is the parameter of the Poisson distribution
for the number of points per cluster. Only used for |
verbose |
logical. Should information on tested values/progress be printed? |
Details
For a desired failure probability alpha, the corresponding parameter which is to use
when determining a high-risk zone is found in an iterative procedure. The simulation procedure
is the same as in eval_method
. In every iteration,
the number of high-risk zones with at least one unobserved event located outside is
compared with the desired failure probability. If necessary, the value of cutoff
is
increased or decreased. The final value alphastar
can than be used in
det_hrz
.
If there are restriction areas in the observation window, use bootcor_restr
instead.
Value
An object of class bootcorr, which consists of a list of the final value for alpha (alphastar
)
and a data.frame course
containing information on the simulation course, e.g. the tested values.
References
Monia Mahling, Michael H?hle & Helmut K?chenhoff (2013), Determining high-risk zones for unexploded World War II bombs by using point process methodology. Journal of the Royal Statistical Society, Series C 62(2), 181-199.
Monia Mahling (2013), Determining high-risk zones by using spatial point process methodology. Ph.D. thesis, Cuvillier Verlag G?ttingen, available online: http://edoc.ub.uni-muenchen.de/15886/ Chapter 6
See Also
det_hrz
, eval_method
, bootcor_restr
Examples
## Not run:
data(craterB)
set.seed(4321)
bc <- bootcor(ppdata=craterB, cutoff=0.2, numit=100, tol=0.02, nxprob=0.1)
bc
summary(bc)
plot(bc)
hrzbc <- det_hrz(craterB, type = "intens", criterion = "indirect",
cutoff = bc$alphastar, nxprob = 0.1)
## End(Not run)