Equivalence of regression curves sharing common parameters Anzeigen

In clinical trials the comparison of two different populations is a frequently addressed problem. Non-linear (parametric) regression models are commonly used to describe the relationship between covariates as the dose and a response variable in the two groups. In some situations it is reasonable to assume some model parameters to be the same, for instance the placebo effect or the maximum treatment effect. In this paper we develop a (parametric) bootstrap test to establish the similarity...

The empirical process of residuals from an inverse regression Anzeigen

In this paper we investigate an indirect regression model characterized by the Radon transformation. This model is useful for recovery of medical images obtained by computed tomography scans. The indirect regression function is estimated using a series estimator motivated by a spectral cut-off technique. Further, we investigate the empirical process of residuals from this regression, and show that it satsifies a functional central limit theorem.

Generalized sign tests based on sign depth Anzeigen

We introduce generalized sign tests based on K-sign depth, shortly denoted by K-depth. These so-called K-depth tests are motivated by simplicial regression depth. Since they depend only on the signs of the residuals, these test statistics are easy to comprehend and outlier robust. We show that the K-depth test with K = 2 is equivalent to the classical sign test so that K-depth tests with K > 2 are generalizations of the classical sign test. Since the K-depth test with K = 2 is equivalen...

A generalized method of moments estimator for structural vector autoregressions based on higher moments Anzeigen

I propose a generalized method of moments estimator for structural vector autoregressions with non-Gaussian shocks. The shocks are identified by exploiting information contained in higher moments of the data. Extending the standard identification approach, which relies on the shocks' covariance, to the shocks' coskewness and cokurtosis allows to identify the simultaneous interaction without any further restrictions. I analyze the estimator's performance depending on the co-moments used ...

Optimal designs for series estimation in nonparametric regression with correlated data Anzeigen

In this paper we investigate the problem of designing experiments for series estimators in nonparametric regression models with correlated observations. We use projection based estimators to derive an explicit solution of the best linear oracle estimator in the continuous time model for all Markovian-type error processes. These solutions are then used to construct estimators, which can be calculated from the available data along with their corresponding optimal design points. Our results are ...

Goodness-of-fit testing the error distribution in multivariate indirect regression Anzeigen

We propose a goodness-of-fit test for the distribution of errors from a multivariate indirect regression model. The test statistic is based on the Khmaladze transformation of the empirical process of standardized residuals. This goodness-of-fit test is consistent at the root-n rate of convergence, and the test can maintain power against local alternatives converging to the null at a root-n rate.

A similarity measure for second order properties of non-stationary functional time series with applications to clustering and testing Anzeigen

Due to the surge of data storage techniques, the need for the development of appropri-ate techniques to identify patterns and to extract knowledge from the resulting enormous data sets, which can be viewed as collections of dependent functional data, is of increasing interest in many scientific areas. We develop a similarity measure for spectral density oper-ators of a collection of functional time series, which is based on the aggregation of Hilbert-Schmidt differences of the individual time...

Aliasing effects for random fields over spheres of arbitrary dimension Anzeigen

In this paper, aliasing effects are investigated for random fields defined on the d-dimensional sphere Sd, and reconstructed from discrete samples. First, we introduce the concept of an aliasing function on Sd. The aliasing function allows to identify explicitly the aliases of a given harmonic coefficient in the Fourier decomposition. Then, we exploit this tool to establish the aliases of the harmonic coefficients approximated by means of the quadrature procedure named spherical uniform samp...

Increased market transparency in Germany’s gasoline market: The death of rockets and feathers? Anzeigen

Drawing on a consumer search model and a unique panel data set of daily fuel prices covering over 5,000 fuel stations in Germany, this paper documents a change in the price setting behavior of retail gas stations following the introduction of a legally mandated on-line price portal. Prior to the introduction of the portal in 2013, positive asymmetry is found on the basis of error correction models, with prices following the “rockets and feathers” pattern documented in many commodity mark...

Statistical analysis of the lifetime of diamond impregnated tools for core drilling of concrete Anzeigen

The lifetime of diamond impregnated tools for core drilling of concrete is studied via the lifetimes of the single diamonds on the tool. Thereby, the number of visible and active diamonds on the tool surface is determined by microscopical inspections of the tool at given points in time. This leads to interval-censored lifetime data if only the diamonds visible at the beginning are considered. If also the lifetimes of diamonds appearing during the drilling process are included then the l...

Detection of anomalous sequences in crack data of a bridge monitoring Anzeigen

For estimating the remaining lifetime of old prestressed concrete bridges, a monitoring of crack widths can be used. However, the time series of crack widths show a strong variation mainly caused by temperature and traffic. Additionally, sequences with extreme volatility appear where the cause is unknown. They are called anomalous sequences in the following.We present and compare four methods which aim to detect these anomalous sequences in the time series. Volatilities caused by traffi...

Multiscale change point detection for dependent data Anzeigen

In this paper we study the theoretical properties of the simultaneous multiscale change point estimator (SMUCE) proposed by Frick et al. (2014) in regression models with dependent error processes. Empirical studies show that in this case the change point estimate is inconsistent, but it is not known if alternatives suggested in the literature for correlated data are consistent. We propose a modification of SMUCE scaling the basic statistic by the long run variance of the error process, w...

Panel cointegrating polynomial regressions: Group-mean fully modified OLS estimation and inference Anzeigen

This paper considers group-mean fully modified OLS estimation for a panel of cointegrating polynomial regressions, i. e., regressions that include an integrated process and its powers as explanatory variables. The stationary errors are allowed to be serially correlated, the regressor to be endogenous and { as usual in the nonstationary panel literature { we include individual specific fixed effects. We consider a fixed cross-section dimension, asymptotics in the time dimension only and s...

Consistency for the negative binomial regression with fixed covariate Anzeigen

We model an overdispersed count as a dependent measurement, by means of the Negative Binomial distribution. We consider quantitative regressors that are fixed by design. The expectation of the dependent variable is assumed to be a known function of a linear combination involving regressors and their coefficients. In the NB1-parametrization of the negative binomial distribution, the variance is a linear function of the expectation, inflated by the dispersion parameter, and not a generalized...

Using the extremal index for value-at-risk backtesting Anzeigen

We introduce a set of new Value-at-Risk independence backtests by establishing a connection between the independence property of Value-at-Risk forecasts and the extremal index, a general measure of extremal clustering of stationary sequences. We introduce a sequence of relative excess returns whose extremal index has to be estimated. We compare our backtest to both popular and recent competitors using Monte-Carlo simulations and find considerable power in many scenarios. In an applied s...

Switching to green electricity: Spillover effects on household consumption Anzeigen

One way to reduce emissions from the consumption of electricity is switching to green electricity suppliers. This paper identifies the determinants of adopting green electricity and the effect on electricity consumption, using panel data on more than 9,000 households. To control for potential self-selection into green electricity tariffs, an endogenous dummy treatment effects model is estimated. The results suggest that wealthier and better-educated households are more likely to adopt gr...

RISE Germany Internship: Applying Deep Learning Methods to the Search for Astrophysical Tau Neutrinos Anzeigen

Feature Selection for High-Dimensional Data with RapidMiner Anzeigen

Feature selection is an important task in machine learning, reducing dimensionality of learning problems by selecting few relevant features without losing too much information. Focusing on smaller sets of features, we can learn simpler models from data that are easier to understand and to apply. In fact, simpler models are more robust to input noise and outliers, often leading to better prediction performance than the models trained in higher dimensions with all features. We implement several...

Energy-Efficient GPS-Based Positioning in the Android Operating System Anzeigen

We present our ongoing collaborative work on EnDroid, an energy-efficient GPS-based positioning system for the Android Operating System. EnDroid is based on the EnTracked positioning system, developed at the University of Aarhus, Denmark. We describe the current prototypical state of our implementation and present our experiences and conclusions from preliminarily evaluating EnDroid on the Google Nexus One Smartphone. Although the preliminary results seem to sup- port the approach, there are...