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Limits of the Allan Variance and Optimal Tuning of Wavelet Variance based Estimators

This article first demonstrates the inconsistency of the estimator based on the standard Allan Variance (AV) for composite stochastic processes. This result motivates the use of a recently developed estimator, called the Generalized Method of Wavelet Moments (GMWM) estimator. This estimator was previously shown to be consistent and asymptotically normally distributed under the...

Institution partenaire

Université de Genève

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English / 01/01/2013

N-acetylcysteine does not prevent contrast nephropathy in patients with renal impairment undergoing emergency CT: a randomized study

BACKGROUND: Patients admitted to the emergency room with renal impairment and undergoing a contrast computed tomography (CT) are at high risk of developing contrast nephropathy as emergency precludes sufficient hydration prior to contrast use. The value of an ultra-high dose of intravenous N-acetylcysteine in this setting is unknown. METHODS: From 2008 to 2010, we randomized 120...

Institution partenaire

Université de Genève

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English / 01/01/2013

An Algorithm for Automatic Inertial Sensors Calibration : Proceedings of the ION GNSS 2013

We present an algorithm for determining the nature of stochastic processes together with its parameters based on the analysis of time series of inertial errors. The algorithm is suitable mainly (but not only) for situations when several stochastic processes are superposed. In such cases, classical approaches based on the analysis of Allan variance or PSD are likely to fail due to the...

Institution partenaire

Université de Genève

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English / 01/01/2013

Robust Estimation of Bivariate Copulas

Copula functions are very convenient for modelling multivariate observations. Popular es- timation methods are the two-stage maximum likelihood and an alternative semi-parametric with empirical cumulative distribution functions (cdf) for the margins. Unfortunately, they can be hastily biased whenever relatively small model deviations occur at the marginal (empirical or parametric)...

Institution partenaire

Université de Genève

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English / 01/01/2013

Robust Estimation for Bivariate Distribution

Copula functions are very convenient for modelling multivariate observations. Popular estimation methods are the two-stage MLE and an alternative semi-parametric with empirical cdf for the margins. Unfortunately, they are hastily biased whenever relatively small model deviations occur at the marginal (empirical or parametric) and/or copula levels. In this master thesis we propose...

Institution partenaire

Université de Genève

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English / 01/01/2013

Economic Theory and Minority Language

Institution partenaire

Université de Genève

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English / 01/01/2013

Wavelet-Variance-Based Estimation for Composite Stochastic Processes

This article presents a new estimationmethod for the parameters of a times series model.We consider here composite Gaussian processes that are the sum of independent Gaussian processes which, in turn, explain an important aspect of the time series, as is the case in engineering and natural sciences. The proposed estimation method offers an alternative to classical estimation based on...

Institution partenaire

Université de Genève

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English / 01/01/2013

Extreme spillover between shadow banking and regular banking

The current financial crisis brought light to a large banking sector that existed for decades within the "darkness" of the financial system - the shadow banking sector. Shadow bank assets are widely traded in the financial markets and shadow banking activities are intertwined with the daily business of regular banks. This unregulated banking sector has become systematically...

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English / 01/01/2013

Modeling non-maturing savings volumes

In Basel II the regulators stress the importance of finding realistic volumes models for non-maturing accounts (NMAs), given their cash-flow uncer- tainty due to optionality. Focusing on Swiss savings accounts, we identify their seasonal pattern and we derive their sensitivity to market rates and to relevant macroeconomic factors. We derive a realistic volumes model, that allows for...

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English / 02/07/2012

Fault Detection and Isolation in Multiple MEMS-IMUs Configurations

This research presents methods for detecting and isolating faults in multiple MEMS-IMU configurations. First, geometric configurations with n sensor triads are investigated. It is proofed that the relative orientation between sensor triads is irrelevant to system optimality in the absence of failures. Then, the impact of sensor failure or decreased performance is investigated. Three...

Institution partenaire

Université de Genève

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English / 01/01/2012

A Prediction Divergence Criterion for Model Selection

In this paper, we propose a new criterion for selection between nested models. We suppose that the correct model is one (or near one) of the available models and construct a criterion which is based on the Bregman divergence between the out-of-sample prediction of the smaller model and the in-sample prediction of the larger model. This criterion, the prediction divergence criterion (...

Institution partenaire

Université de Genève

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English / 01/01/2012

A Framework for Inertial Sensor Calibration using Complex Stochastic Error Models, in the proceedings of the Position Location and Navigation Symposium (PLANS), 2012 IEEE/ION

Modeling and estimation of gyroscope and accelerometer errors is generally a very challenging task, especially for low-cost inertial MEMS sensors whose systematic errors have complex spectral structures. Consequently, identifying correct error-state parameters in a INS/GNSS Kalman filter/smoother becomes difficult when several processes are superimposed. In such situations, the...

Institution partenaire

Université de Genève

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English / 01/01/2012

Robust filtering

Filtering methods are powerful tools to estimate the hidden state of a statespace model from observations available in real time. However, they are known to be highly sensitive to the presence of small misspecifications of the underlying model and to outliers in the observation process. In this paper, we show that the methodology of robust statistics can be adapted to sequential...

Institution partenaire

Université de Genève

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English / 01/01/2012

Fast Robust Model Selection in Large Datasets

Large datasets are more and more common in many research fields. In particular, in the linear regression context, it is often the case that a huge number of potential covariates are available to explain a response variable, and the first step of a reasonable statistical analysis is to reduce the number of covariates. This can be done in a forward selection procedure that includes the...

Institution partenaire

Université de Genève

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English / 01/01/2011

Isotone additive latent variable models

For manifest variables with additive noise and for a given number of latent variables with an assumed distribution, we propose to nonparametrically estimate the association between latent and manifest variables. Our estimation is a two step procedure: first it employs standard factor analysis to estimate the latent variables as theoretical quantiles of the assumed distribution;...

Institution partenaire

Université de Genève

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English / 01/01/2011

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