60,457 research outputs found
Assessing Compatibility of Direct Detection Data: Halo-Independent Global Likelihood Analyses
We present two different halo-independent methods to assess the compatibility
of several direct dark matter detection data sets for a given dark matter model
using a global likelihood consisting of at least one extended likelihood and an
arbitrary number of Gaussian or Poisson likelihoods. In the first method we
find the global best fit halo function (we prove that it is a unique piecewise
constant function with a number of down steps smaller than or equal to a
maximum number that we compute) and construct a two-sided pointwise confidence
band at any desired confidence level, which can then be compared with those
derived from the extended likelihood alone to assess the joint compatibility of
the data. In the second method we define a "constrained parameter
goodness-of-fit" test statistic, whose -value we then use to define a
"plausibility region" (e.g. where ). For any halo function not
entirely contained within the plausibility region, the level of compatibility
of the data is very low (e.g. ). We illustrate these methods by
applying them to CDMS-II-Si and SuperCDMS data, assuming dark matter particles
with elastic spin-independent isospin-conserving interactions or exothermic
spin-independent isospin-violating interactions.Comment: 31 pages, 6 figures. V2: Modified several paragraphs to improve
clarify. Modified Fig. 5 and added Fig. 6 to further illustrate methods of
Section 5. Added proof of uniqueness of best fit halo function in Appendix
Plausibility functions and exact frequentist inference
In the frequentist program, inferential methods with exact control on error
rates are a primary focus. The standard approach, however, is to rely on
asymptotic approximations, which may not be suitable. This paper presents a
general framework for the construction of exact frequentist procedures based on
plausibility functions. It is shown that the plausibility function-based tests
and confidence regions have the desired frequentist properties in finite
samples---no large-sample justification needed. An extension of the proposed
method is also given for problems involving nuisance parameters. Examples
demonstrate that the plausibility function-based method is both exact and
efficient in a wide variety of problems.Comment: 21 pages, 5 figures, 3 table
Large-Scale Structure in the NIR-Selected MUNICS Survey
The Munich Near-IR Cluster Survey (MUNICS) is a wide-area, medium-deep,
photometric survey selected in the K' band. The project's main scientific aims
are the identification of galaxy clusters up to redshifts of unity and the
selection of a large sample of field early-type galaxies up to z < 1.5 for
evolutionary studies. We created a Large Scale Structure catalog, using a new
structure finding technique specialized for photometric datasets, that we
developed on the basis of a friends-of-friends algorithm. We tested the
plausibility of the resulting galaxy group and cluster catalog with the help of
Color-Magnitude Diagrams (CMD), as well as a likelihood- and Voronoi-approach.Comment: 4 pages, to appear in "The Evolution of Galaxies III. From Simple
Approaches to Self-Consistent Models", proceedings of the 3rd EuroConference
on the evolution of galaxies, held in Kiel, Germany, July 16-20, 200
Random sets and exact confidence regions
An important problem in statistics is the construction of confidence regions
for unknown parameters. In most cases, asymptotic distribution theory is used
to construct confidence regions, so any coverage probability claims only hold
approximately, for large samples. This paper describes a new approach, using
random sets, which allows users to construct exact confidence regions without
appeal to asymptotic theory. In particular, if the user-specified random set
satisfies a certain validity property, confidence regions obtained by
thresholding the induced data-dependent plausibility function are shown to have
the desired coverage probability.Comment: 14 pages, 2 figure
Analysis of the Web Graph Aggregated by Host and Pay-Level Domain
In this paper the web is analyzed as a graph aggregated by host and pay-level
domain (PLD). The web graph datasets, publicly available, have been released by
the Common Crawl Foundation and are based on a web crawl performed during the
period May-June-July 2017. The host graph has 1.3 billion nodes and
5.3 billion arcs. The PLD graph has 91 million nodes and 1.1
billion arcs. We study the distributions of degree and sizes of strongly/weakly
connected components (SCC/WCC) focusing on power laws detection using
statistical methods. The statistical plausibility of the power law model is
compared with that of several alternative distributions. While there is no
evidence of power law tails on host level, they emerge on PLD aggregation for
indegree, SCC and WCC size distributions. Finally, we analyze distance-related
features by studying the cumulative distributions of the shortest path lengths,
and give an estimation of the diameters of the graphs
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