2,378 research outputs found
Polling bias and undecided voter allocations: US Presidential elections, 2004 - 2016
Accounting for undecided and uncertain voters is a challenging issue for
predicting election results from public opinion polls. Undecided voters typify
the uncertainty of swing voters in polls but are often ignored or allocated to
each candidate in a simple, deterministic manner. Historically this may have
been adequate because the undecided were comparatively small enough to assume
that they do not affect the relative proportions of the decided voters.
However, in the presence of high numbers of undecided voters, these static
rules may in fact bias election predictions from election poll authors and
meta-poll analysts. In this paper, we examine the effect of undecided voters in
the 2016 US presidential election to the previous three presidential elections.
We show there were a relatively high number of undecided voters over the
campaign and on election day, and that the allocation of undecided voters in
this election was not consistent with two-party proportional (or even)
allocations. We find evidence that static allocation regimes are inadequate for
election prediction models and that probabilistic allocations may be superior.
We also estimate the bias attributable to polling agencies, often referred to
as "house effects".Comment: 32 pages, 9 figures, 6 table
Strongly Coupled Quark Gluon Plasma (SCQGP)
We propose that the reason for the non-ideal behavior seen in lattice
simulation of quark gluon plasma (QGP) and relativistic heavy ion collisions
(URHICs) experiments is that the QGP near T_c and above is strongly coupled
plasma (SCP), i.e., strongly coupled quark gluon plasma (SCQGP). It is
remarkable that the widely used equation of state (EoS) of SCP in QED (quantum
electrodynamics) very nicely fits lattice results on all QGP systems, with
proper modifications to include color degrees of freedom and running coupling
constant. Results on pressure in pure gauge, 2-flavors and 3-flavors QGP, are
all can be explained by treating QGP as SCQGP as demonstated here.Energy
density and speed of sound are also presented for all three systems. We further
extend the model to systems with finite quark mass and a reasonably good fit to
lattice results are obtained for (2+1)-flavors and 4-flavors QGP. Hence it is
the first unified model, namely SCQGP, to explain the non-ideal QGP seen in
lattice simulations with just two system dependent parameters.Comment: Revised with corrections and new results, Latex file (11 pages),
postscript file of 7 figure
THERMAL RADIATION FROM MAGNETIZED NEUTRON STARS: A look at the Surface of a Neutron Star.
Surface thermal emission has been detected by ROSAT from four nearby young
neutron stars. Assuming black body emission, the significant pulsations of the
observed light curves can be interpreted as due to large surface temperature
differences produced by the effect of the crustal magnetic field on the flow of
heat from the hot interior toward the cooler surface. However, the energy
dependence of the modulation observed in Geminga is incompatible with blackbody
emission: this effect will give us a strong constraint on models of the neutron
star surface.Comment: 10 pages. tar-compressed and uuencoded postcript file. talk given at
the `Jubilee Gamow Seminar', St. Petersburg, Sept. 1994
Spendthrifts and Tightwads in Childhood: Feelings about Spending Predict Childrenâs Financial Decision Making
Adults differ in the extent to which they find spending money to be distressing; âtightwadsâ find spending money painful, and âspendthriftsâ do not find spending painful enough. This affective dimension has been reliably measured in adults and predicts a variety of important financial behaviors and outcomes (e.g., saving behavior and credit scores). Although childrenâs financial behavior has also received attention, feelings about spending have not been studied in children, as they have in adults. We measured the spendthriftâtightwad (STâTW) construct in children for the first time, with a sample of 5â to 10âyearâold children (N = 225). Children across the entire age range were able to reliably report on their affective responses to spending and saving, and childrenâs STâTW scores were related to parent reports of childrenâs temperament and financial behavior. Further, childrenâs STâTW scores were predictive of whether they chose to save or spend money in the lab, even after controlling for age and how much they liked the offered items. Our novel findingsâthat childrenâs feelings about spending and saving can be measured from an early age and relate to their behavior with moneyâare discussed with regard to theoretical and practical implications. Copyright © 2017 John Wiley & Sons, Ltd.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/144659/1/bdm2071_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144659/2/bdm2071.pd
Moving Beyond Noninformative Priors: Why and How to Choose Weakly Informative Priors in Bayesian Analyses
Throughout the last two decades, Bayesian statistical methods have proliferated throughout ecology and evolution. Numerous previous references established both philosophical and computational guidelines for implementing Bayesian methods. However, protocols for incorporating prior information, the defining characteristic of Bayesian philosophy, are nearly nonexistent in the ecological literature. Here, I hope to encourage the use of weakly informative priors in ecology and evolution by providing a âconsumer\u27s guideâ to weakly informative priors. The first section outlines three reasons why ecologists should abandon noninformative priors: 1) common flat priors are not always noninformative, 2) noninformative priors provide the same result as simpler frequentist methods, and 3) noninformative priors suffer from the same high type I and type M error rates as frequentist methods. The second section provides a guide for implementing informative priors, wherein I detail convenient âreferenceâ prior distributions for common statistical models (i.e. regression, ANOVA, hierarchical models). I then use simulations to visually demonstrate how informative priors influence posterior parameter estimates. With the guidelines provided here, I hope to encourage the use of weakly informative priors for Bayesian analyses in ecology. Ecologists can and should debate the appropriate form of prior information, but should consider weakly informative priors as the new âdefaultâ prior for any Bayesian model
Not all surveillance data are created equalâA multiâmethod dynamic occupancy approach to determine rabies elimination from wildlife
1. A necessary component of elimination programmes for wildlife disease is effective surveillance. The ability to distinguish between disease freedom and nonâdetection can mean the difference between a successful elimination campaign and new epizootics. Understanding the contribution of different surveillance methods helps to optimize and better allocate effort and develop more effective surveillance programmes.
2. We evaluated the probability of rabies virus elimination (disease freedom) in an enzootic area with active management using dynamic occupancy modelling of 10 years of raccoon rabies virus (RABV) surveillance data (2006â2015) collected from three states in the eastern United States. We estimated detection probability of RABV cases for each surveillance method (e.g. strange acting reports, roadkill, surveillanceâtrapped animals, nuisance animals and public health samples) used by the USDA National Rabies Management Program.
3. Strange acting, found dead and public health animals were the most likely to detect RABV when it was present, and generally detectability was higher in fallâ winter compared to springâsummer. Found dead animals in fallâwinter had the highest detection at 0.33 (95% CI: 0.20, 0.48). Nuisance animals had the lowest detection probabilities (~0.02).
4. Areas with oral rabies vaccination (ORV) management had reduced occurrence probability compared to enzootic areas without ORV management. RABV occurrence was positively associated with deciduous and mixed forests and medium to high developed areas, which are also areas with higher raccoon (Procyon lotor) densities. By combining occupancy and detection estimates we can create a probability of elimination surface that can be updated seasonally to provide guidance on areas managed for wildlife disease.
5. Synthesis and applications. Wildlife disease surveillance is often comprised of a combination of targeted and convenienceâbased methods. Using a multiâmethod analytical approach allows us to compare the relative strengths of these methods, providing guidance on resource allocation for surveillance actions. Applying this multiâmethod approach in conjunction with dynamic occupancy analyses better informs management decisions by understanding ecological drivers of disease occurrence
Evidence for the disintegration of KIC 12557548 b
Context. The Kepler object KIC 12557548 b is peculiar. It exhibits
transit-like features every 15.7 hours that vary in depth between 0.2% and
1.2%. Rappaport et al. (2012) explain the observations in terms of a
disintegrating, rocky planet that has a trailing cloud of dust created and
constantly replenished by thermal surface erosion. The variability of the
transit depth is then a consequence of changes in the cloud optical depth.
Aims. We aim to validate the disintegrating-planet scenario by modeling the
detailed shape of the observed light curve, and thereby constrain the cloud
particle properties to better understand the nature of this intriguing object.
Methods. We analysed the six publicly-available quarters of raw Kepler data,
phase-folded the light curve and fitted it to a model for the trailing dust
cloud. Constraints on the particle properties were investigated with a
light-scattering code. Results. The light curve exhibits clear signatures of
light scattering and absorption by dust, including a brightening in flux just
before ingress correlated with the transit depth and explained by forward
scattering, and an asymmetry in the transit light curve shape, which is easily
reproduced by an exponentially decaying distribution of optically thin dust,
with a typical grain size of 0.1 micron. Conclusions. Our quantitative analysis
supports the hypothesis that the transit signal of KIC 12557548 b is due to a
variable cloud of dust, most likely originating from a disintegrating object.Comment: 5 pages, 4 figures. Accepted for publication in Astronomy and
Astrophysic
An Analysis of the Chemical Composition of the Atmosphere of Venus on an AMS of the Venera-12 Using a Gas Chromatograph
Eight analyses of the atmosphere of Venus were made beginning at an altitude of 42 km right down to the surface of the planet. The following were detected in the atmosphere of Venus: nitrogen in concentrations of 2.5 plus or minus 0.5 volumetric %, argon ir concentrations (4 plus or minus 2) x 10 to the minus 3 power volumetric %, CO--(2.8 plus or minus 1.4) x 10 to the minus 3 power volumetric % and SO2 in concentrations (1.3 plus or minus 0.6) x 10 to the minus 2 power volumetric %. The upper limits were estimated for the content of oxygen and water equal to 2 x 10 to the minus 3 power and 10 to the minus 2 power volumetric %, respectively
Radial velocity planets de-aliased. A new, short period for Super-Earth 55 Cnc e
Radial velocity measurements of stellar reflex motion have revealed many
extrasolar planets, but gaps in the observations produce aliases, spurious
frequencies that are frequently confused with the planets' orbital frequencies.
In the case of Gl 581 d, the distinction between an alias and the true
frequency was the distinction between a frozen, dead planet and a planet
possibly hospitable to life (Udry et al. 2007; Mayor et al. 2009). To improve
the characterization of planetary systems, we describe how aliases originate
and present a new approach for distinguishing between orbital frequencies and
their aliases. Our approach harnesses features in the spectral window function
to compare the amplitude and phase of predicted aliases with peaks present in
the data. We apply it to confirm prior alias distinctions for the planets GJ
876 d and HD 75898 b. We find that the true periods of Gl 581 d and HD 73526
b/c remain ambiguous. We revise the periods of HD 156668 b and 55 Cnc e, which
were afflicted by daily aliases. For HD 156668 b, the correct period is 1.2699
days and minimum mass is (3.1 +/- 0.4) Earth masses. For 55 Cnc e, the correct
period is 0.7365 days -- the shortest of any known planet -- and minimum mass
is (8.3 +/- 0.3) Earth masses. This revision produces a significantly improved
5-planet Keplerian fit for 55 Cnc, and a self-consistent dynamical fit
describes the data just as well. As radial velocity techniques push to
ever-smaller planets, often found in systems of multiple planets,
distinguishing true periods from aliases will become increasingly important.Comment: Accepted by ApJ (in press); 19 pages, 22 figures. Fixed typos;
improved wording; added more extensive discussion of orbital eccentricity;
improved figure captions; additional reference
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