An object of class "htest"
(i.e., hypothesis test) function
which performs a hypothesis test of complete spatial
randomness (CSR) or uniformity of Xp
points
in the convex hull of Yp
points against the alternatives
of segregation (where Xp
points cluster away from Yp
points
i.e., cluster around the centers of the Delaunay triangles)
and association (where Xp
points cluster around Yp
points)
based on the (asymptotic) binomial distribution of the
domination number of PE-PCD for uniform 2D data
in the convex hull of Yp
points.
The function yields the test statistic,
\(p\)-value for the corresponding alternative
,
the confidence interval,
estimate and null value for the parameter of interest
(which is \(Pr(\)domination number\(\le 2)\)),
and method and name of the data set used.
Under the null hypothesis of uniformity of Xp
points
in the convex hull of Yp
points, probability of success
(i.e., \(Pr(\)domination number\(\le 2)\)) equals
to its expected value under the uniform distribution) and
alternative
could be two-sided, or right-sided
(i.e., data is accumulated
around the Yp
points, or association)
or left-sided (i.e., data is accumulated
around the centers of the triangles, or segregation).
PE proximity region is constructed
with the expansion parameter \(r \ge 1\) and \(M\)-vertex regions
where \(M\) is a center
that yields non-degenerate asymptotic distribution
of the domination number.
The test statistic is based on the binomial distribution,
when success is defined as domination number being less than
or equal to 2 in the one triangle case
(i.e., number of failures is equal
to number of times restricted domination number = 3
in the triangles).
That is, the test statistic is based on the domination number
for Xp
points inside convex hull of Yp
points
for the PE-PCD and default convex hull correction, ch.cor
,
is FALSE
where M
is the center
that yields nondegenerate asymptotic distribution
for the domination number.
For this approximation to work,
number of Xp
points must be at least 7 times more than
number of Yp
points.
PE proximity region is constructed
with the expansion parameter \(r \ge 1\) and \(CM\)-vertex regions
(i.e., the test is not available for a general center \(M\)
at this version of the function).
**Caveat:** This test is currently a conditional test,
where Xp
points are assumed to be random,
while Yp
points are
assumed to be fixed (i.e., the test is conditional on Yp
points).
Furthermore, the test is a large sample test
when Xp
points are substantially larger than Yp
points,
say at least 7 times more.
This test is more appropriate
when supports of Xp
and Yp
have a substantial overlap.
Currently, the Xp
points
outside the convex hull of Yp
points
are handled with a convex hull correction factor
(see the description below and the function code.)
Removing the conditioning
and extending it to the case of non-concurring supports is
an ongoing topic of research of the author of the package.
See also (ceyhan:dom-num-NPE-Spat2011;textualpcds).