ENBIS: European Network for Business and Industrial Statistics
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ENBIS14 in Linz
21 – 25 September 2014; Johannes Kepler University, Linz, Austria Abstract submission: 23 January – 22 June 2014The following abstracts have been accepted for this event:

Nonparametric Estimation and Forecasting of Time Series with Deterministic Trend and Season and Traffic Fatalities in Germany
Authors: Harry Haupt (University of Passau), Joachim Schnurbus (University of Passau)
Primary area of focus / application: Economics
Secondary area of focus / application: Modelling
Keywords: Mixed kernel forecasting, Smoothing, Deterministic trend and season, Break points
Submitted at 28Apr2014 18:32 by Joachim Schnurbus
Accepted

An Inverse Problem to Simulate the Degradation Process of Semiconductor Devices
Authors: Barbara Pedretscher (KAI Kompetenzzentrum für Automobil und Industrieelektronik GmbH), Olivia Bluder (KAI Kompetenzzentrum für Automobil und Industrieelektronik GmbH), Barbara Kaltenbacher (Alpen Adria Universität Klagenfurt), Kathrin Plankensteiner (KAI Kompetenzzentrum für Automobil und Industrieelektronik GmbH)
Primary area of focus / application: Reliability
Secondary area of focus / application: Modelling
Keywords: Semiconductor Reliability, Modeling Lifetime Data, State Space Model, Adjoint Method
The data contains input parameters of accelerated stress tests (current, voltage, pulse width, repetition time), lifetime data measured in Cycles to Failure (CTF) and special electrical measurements (ATEmeasurements), which are available at predefined stress cycles. It is assumed that the mentioned ATEmeasurements are indicators for the progress of the degradation.
A state space model combines state variables with input and output data via a state differential equation and an observation equation. In this context CTFs, modeled by first passage times, and ATEmeasurements belong to the output.
Since crack propagation and the implied increasing temperature are the main reasons for device failure, we model an interacting system of differential equations with two state variables, which map the time behavior of these failure causes. Usually, the crack propagation is modeled by the Paris law dependent on the stress range. Since wafer bow measurements on the metallization of interest indicate that the stress range is in the plastic regime, meaning that the stress does not change significantly with small changes in the temperature rise, the temperature dependent strain is used for modeling instead. For this purpose, Hooke’s formula, which provides a connection between the stress range, the strain and the modulus of elasticity, is used. Measurements show that even the modulus of elasticity can be modeled temperature dependently.
The temperature rise in the device can be modeled by the input parameters of the lifetime test and a thermal coefficient reflecting the material properties. The input parameters do not change over testing time, but the temperature rise in the device under test increases; hence the thermal coefficient is directly proportional to the temperature rise. Generally spoken, the coefficient mirrors the thermal connection of the material layers in the device. Since it needs to tend towards a saturation level we use a logistic curve to model its behavior. Thus, the state variables are given by the degradation, modeled via the crack propagation, and the thermal coefficient.
Due to a high number of unknown parameters compared to available measurements, the parameter estimation is challenging. Under the assumption of normal distributed measurement errors the loglikelihood function can be used as a cost function. For efficient minimization the gradient of the loglikelihood function with respect to the parameters is needed. To avoid expensive calculation of sensitivities an adjoint method, using Lagrange multipliers is applied. 
Towards More Reliable Analysis of Nonregular Designs
Authors: John Tyssedal (The Norwegian University of Science and Technology)
Primary area of focus / application: Design and analysis of experiments
Keywords: Factor based, Nonregular designs, Projection properties, Screening
Submitted at 29Apr2014 11:51 by John Tyssedal
Accepted

Factor Screening in NonRegular TwoLevel Designs based on Projection Based Variable Selection
Authors: Shahrukh Hussain (Department of Mathematics), John Sølve Tyssedal (Department of Mathematics)
Primary area of focus / application: Design and analysis of experiments
Secondary area of focus / application: Design and analysis of experiments
Keywords: Screening, Non regular designs, PB design, Multiple determination
Submitted at 29Apr2014 12:57 by Shahrukh Hussain
Accepted

Statistical Literacy of Business Students
Authors: Christine Duller (Johannes Kepler University Linz)
Primary area of focus / application: Education & Thinking
Keywords: Dtatistical thinking, Teaching statistics, Education, Empirical study
Submitted at 29Apr2014 15:10 by Christine Duller
Accepted
The results were not very glorious, even majority was not always right, as some examples show. The samples show that most of the students have serious difficulties in interpreting "statistical" diagrams and also problems in very basic mathematics. 
Redefining Maintenance Events: A Study of LoadHaul Dump Machines
Authors: Chris McCollin (Nottingham Trent University)
Primary area of focus / application: Reliability
Keywords: Maintenance, Differential equations, Nonhomogeneous poisson processes, Loadhaul dump machines
Submitted at 29Apr2014 15:38 by Chris McCollin
Accepted
Differential equations are then developed to explain the operations and maintenance aspects of systems. These are compared with wellknown differential equation structures. A comparison is made with existing nonhomogeneous Poisson process models. The physical structure of systems event data is shown graphically and the model obtained is applied to a wellknown data set. Comments on the meaning of the structure, the interrelationship of the components within the system and future work is discussed.