5,927 research outputs found
Persistence of political partisanship : evidence from 9/11
This paper empirically examines whether the act of deciding to support a political party can impact partisan leanings years later. We use the discontinuity in the probability of being registered to vote around the 18th birthday to look at the impact of registration after the 9/11/01 attacks on party of registration. We first show that 9/11 increased Republican registration by approximately 2%. Surprisingly, these di¤erences in registration patterns fully persist over the two year period from 2006 to 2008, even for a group of registrants who moved and changed their registration address. We find full persistence for those registered in zip codes within two miles of a four year university, suggesting that persistence is unlikely to be explained by lack of easy access to or inability to process information. Instead, we suggest an interpretation of our findings based upon either cognitive or social biases
Combining Functional Data Registration and Factor Analysis
We extend the definition of functional data registration to encompass a
larger class of registered functions. In contrast to traditional registration
models, we allow for registered functions that have more than one primary
direction of variation. The proposed Bayesian hierarchical model simultaneously
registers the observed functions and estimates the two primary factors that
characterize variation in the registered functions. Each registered function is
assumed to be predominantly composed of a linear combination of these two
primary factors, and the function-specific weights for each observation are
estimated within the registration model. We show how these estimated weights
can easily be used to classify functions after registration using both
simulated data and a juggling data set.Comment: The paper was updated with a better real data exampl
A surgical system for automatic registration, stiffness mapping and dynamic image overlay
In this paper we develop a surgical system using the da Vinci research kit
(dVRK) that is capable of autonomously searching for tumors and dynamically
displaying the tumor location using augmented reality. Such a system has the
potential to quickly reveal the location and shape of tumors and visually
overlay that information to reduce the cognitive overload of the surgeon. We
believe that our approach is one of the first to incorporate state-of-the-art
methods in registration, force sensing and tumor localization into a unified
surgical system. First, the preoperative model is registered to the
intra-operative scene using a Bingham distribution-based filtering approach. An
active level set estimation is then used to find the location and the shape of
the tumors. We use a recently developed miniature force sensor to perform the
palpation. The estimated stiffness map is then dynamically overlaid onto the
registered preoperative model of the organ. We demonstrate the efficacy of our
system by performing experiments on phantom prostate models with embedded stiff
inclusions.Comment: International Symposium on Medical Robotics (ISMR 2018
Hierarchical Bayesian auto-regressive models for large space time data with applications to ozone concentration modelling
Increasingly large volumes of space-time data are collected everywhere by mobile computing applications, and in many of these cases temporal data are obtained by registering events, for example telecommunication or web traffic data. Having both the spatial and temporal dimensions adds substantial complexity to data analysis and inference tasks. The computational complexity increases rapidly for fitting Bayesian hierarchical models, as such a task involves repeated inversion of large matrices. The primary focus of this paper is on developing space-time auto-regressive models under the hierarchical Bayesian setup. To handle large data sets, a recently developed Gaussian predictive process approximation method (Banerjee et al. [1]) is extended to include auto-regressive terms of latent space-time processes. Specifically, a space-time auto-regressive process, supported on a set of a smaller number of knot locations, is spatially interpolated to approximate the original space-time process. The resulting model is specified within a hierarchical Bayesian framework and Markov chain Monte Carlo techniques are used to make inference. The proposed model is applied for analysing the daily maximum 8-hour average ground level ozone concentration data from 1997 to 2006 from a large study region in the eastern United States. The developed methods allow accurate spatial prediction of a temporally aggregated ozone summary, known as the primary ozone standard, along with its uncertainty, at any unmonitored location during the study period. Trends in spatial patterns of many features of the posterior predictive distribution of the primary standard, such as the probability of non-compliance with respect to the standard, are obtained and illustrated
Joint Modeling and Registration of Cell Populations in Cohorts of High-Dimensional Flow Cytometric Data
In systems biomedicine, an experimenter encounters different potential
sources of variation in data such as individual samples, multiple experimental
conditions, and multi-variable network-level responses. In multiparametric
cytometry, which is often used for analyzing patient samples, such issues are
critical. While computational methods can identify cell populations in
individual samples, without the ability to automatically match them across
samples, it is difficult to compare and characterize the populations in typical
experiments, such as those responding to various stimulations or distinctive of
particular patients or time-points, especially when there are many samples.
Joint Clustering and Matching (JCM) is a multi-level framework for simultaneous
modeling and registration of populations across a cohort. JCM models every
population with a robust multivariate probability distribution. Simultaneously,
JCM fits a random-effects model to construct an overall batch template -- used
for registering populations across samples, and classifying new samples. By
tackling systems-level variation, JCM supports practical biomedical
applications involving large cohorts
Spatial-temporal data mining procedure: LASR
This paper is concerned with the statistical development of our
spatial-temporal data mining procedure, LASR (pronounced ``laser''). LASR is
the abbreviation for Longitudinal Analysis with Self-Registration of
large--small- data. It was motivated by a study of ``Neuromuscular
Electrical Stimulation'' experiments, where the data are noisy and
heterogeneous, might not align from one session to another, and involve a large
number of multiple comparisons. The three main components of LASR are: (1) data
segmentation for separating heterogeneous data and for distinguishing outliers,
(2) automatic approaches for spatial and temporal data registration, and (3)
statistical smoothing mapping for identifying ``activated'' regions based on
false-discovery-rate controlled -maps and movies. Each of the components is
of interest in its own right. As a statistical ensemble, the idea of LASR is
applicable to other types of spatial-temporal data sets beyond those from the
NMES experiments.Comment: Published at http://dx.doi.org/10.1214/074921706000000707 in the IMS
Lecture Notes--Monograph Series
(http://www.imstat.org/publications/lecnotes.htm) by the Institute of
Mathematical Statistics (http://www.imstat.org
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