25,801 research outputs found

    The Historical Development of Easter-Southern Freight Rate Relationships

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    A method for creating and presenting video-recorded synchronized audiovisual stimuli at a high frame rate-which would be highly useful for psychophysical studies on, for example, just-noticeable differences and gating-is presented. Methods for accomplishing this include recording audio and video separately using an exact synchronization signal, editing the recordings and finding exact synchronization points, and presenting the synchronized audiovisual stimuli with a desired frame rate on a cathode ray tube display using MATLAB and Psychophysics Toolbox 3. The methods from an empirical gating study (Moradi, Lidestam, and Ronnberg, Frontiers in Psychology 4: 359, 2013) are presented as an example of the implementation of playback at 120 fps

    Prior elicitation in multiple change-point models

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    This paper discusses Bayesian inference in change-point models. Existing approaches involve placing a (possibly hierarchical) prior over a known number of change-points. We show how two popular priors have some potentially undesirable properties (e.g. allocating excessive prior weight to change-points near the end of the sample) and discuss how these properties relate to imposing a fixed number of changepoints in-sample. We develop a new hierarchical approach which allows some of of change-points to occur out-of sample. We show that this prior has desirable properties and handles the case where the number of change-points is unknown. Our hierarchical approach can be shown to nest a wide variety of change-point models, from timevarying parameter models to those with few (or no) breaks. Since our prior is hierarchical, data-based learning about the parameter which controls this variety occurs

    Are apparent findings of nonlinearity due to structural instability in economic time series?

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    Many modelling issues and policy debates in macroeconomics depend on whether macroeconomic times series are best characterized as linear or nonlinear. If departures from linearity exist, it is important to know whether these are endogenously generated (as in, e.g., a threshold autoregressive model) or whether they merely reflect changing structure over time. We advocate a Bayesian approach and show how such an approach can be implemented in practice. An empirical exercise involving several macroeconomic time series shows that apparent findings of threshold type nonlinearities could be due to structural instability

    Institutional Title IX Requirements for Researchers Conducting Human Subjects Research on Sexual Violence and other Forms of Interpersonal Violence

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    The purpose of this white paper is to provide guidance on how university and college Institutional Review Boards (IRBs) and IRB administrators can oversee, and researchers can conduct, research investigating the different aspects of Sexual Violence and other forms of Interpersonal Violence

    A versatile all-channel stimulator for electrode arrays, with real-time control

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    Over the last few decades, technology to record through ever increasing numbers of electrodes has become available to electrophysiologists. For the study of distributed neural processing, however, the ability to stimulate through equal numbers of electrodes, and thus to attain bidirectional communication, is of paramount importance. Here, we present a stimulation system for multi-electrode arrays which interfaces with existing commercial recording hardware, and allows stimulation through any electrode in the array, with rapid switching between channels. The system is controlled through real-time Linux, making it extremely flexible: stimulation sequences can be constructed on-the-fly, and arbitrary stimulus waveforms can be used if desired. A key feature of this design is that it can be readily and inexpensively reproduced in other labs, since it interfaces to standard PC parallel ports and uses only off-the-shelf components. Moreover, adaptation for use with in vivo multi-electrode probes would be straightforward. In combination with our freely available data-acquisition software, MeaBench, this system can provide feedback stimulation in response to recorded action potentials within 15 ms

    Forecasting and Estimating Multiple Change-point Models with an Unknown Number of Change-points

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    This paper develops a new approach to change-point modeling that allows the number of change-points in the observed sample to be unknown. The model we develop assumes regime durations have a Poisson distribution. It approximately nests the two most common approaches: the time varying parameter model with a change-point every period and the change-point model with a small number of regimes. We focus considerable attention on the construction of reasonable hierarchical priors both for regime durations and for the parameters which characterize each regime. A Markov Chain Monte Carlo posterior sampler is constructed to estimate a change-point model for conditional means and variances. Our techniques are found to work well in an empirical exercise involving US GDP growth and inflation. Empirical results suggest that the number of change-points is larger than previously estimated in these series and the implied model is similar to a time varying parameter (with stochastic volatility) model.Bayesian; structural break; Markov Chain Monte Carlo; hierarchical prior

    The dynamics of UK and US inflation expectations

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    This paper investigates the relationship between short term and long term inflation expectations in the US and the UK with a focus on inflation pass through (i.e. how changes in short term expectations affect long term expectations). An econometric methodology is used which allows us to uncover the relationship between inflation pass through and various explanatory variables. We relate our empirical results to theoretical models of anchored, contained and unmoored inflation expectations. For neither country do we find anchored or unmoored inflation expectations. For the US, contained inflation expectations are found. For the UK, our findings are not consistent with the specific model of contained inflation expectations presented here, but are consistent with a more broad view of expectations being constrained by the existence of an inflation target

    Green-Technology Automobiles: Can modern innovations save the environment and consumers\u27 pockets

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    Cars of the past are notorious for poor fuel efficiency and high carbon emissions. With the presence of hybrid technology, along with a variety of other green innovations, many of these negative side effects can be mitigated. The purpose of this study is to answer the question: how do green technology vehicles compare with similar models that exclude such innovations in relation to efficiency and price? A total of 47 green-tech vehicles were identified and compared against their base model counterparts. Vehicle weight, horsepower, fuel efficiency and other variables were matched within pairs (green-tech vs. base) and between car types (sedans, SUVs and trucks). Regardless of vehicle type and green-tech, weight proved to be an influential factor, showing that as curb weight increased, fuel efficiency decreased. Compared to the base models, green-tech luxury vehicles also exhibited few improvements in fuel efficiency with disproportionately high growth in price. Non-luxury green-tech sedans ranging from 2500lbs to 4000lbs showed the largest improvements in efficiency while also maintaining an average MSRP of $28996Ā±1089, producing a green-tech vehicle that is economically affordable. The impressive results from this category of vehicles suggest that consumer investment in non-luxury green sedans may not only help to save money in fuel consumption, but also save the environment

    Prior Elicitation in Multiple Change-point Models

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    This paper discusses Bayesian inference in change-point models. The main existing approaches either attempt to be noninformative by using a Uniform prior over change-points or use an informative hierarchical prior. Both these approaches assume a known number ofchange-points. We show how they have some potentially undesirable properties and discuss how these properties relate to the imposition of a ā€¦xed number of changepoints. We develop a new Uniform prior which allows some of the change-points to occur out-of sample. This prior has desirable properties, can reasonably be interpreted as ā€œnoninformativeā€ and handles the case where the number of change-points is unknown. We show how the general ideas of our approach can be extended to informative hierarchical priors. With artiā€¦cial data and two empirical illustrations, we show how these diĀ¤erent priors can have a substantial impact on estimation and prediction even with moderately large data sets.
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