ENBIS-7 in Dortmund

24 – 26 September 2007

My abstracts

 

The following abstracts have been accepted for this event:

  • Supermarkets Sales and Retail Area: A Mixture Regression Model for Segmentation

    Authors: Ana Oliveira Brochado (1), Castro, Alexandra Carla (2) and Francisco Vitorino Martins (2)
    Primary area of focus / application:
    Submitted at 10-Sep-2007 01:05 by Ana Brochado
    Accepted
    Sales in supermarkets, located across a country, can be explained by a wide range of
    factors as average price, store area for selling, service quality, regional purchasing
    power, population and competition.

    We intend to construct segments of stores (hypermarkets and supermarkets), identifying
    characteristics based on different responsiveness of sales to the different explanatory
    variables.

    We use mixture regression models with a constant elasticity model (power function),
    estimating simultaneously the regression model and the assignment of each store to
    each segment. The number of segments is accessed by statistical indicators, as
    information and classification based criteria.

    Due to the high importance attributed by managers to the retail area elasticity, this
    variable has a special role in this analysis, named on the profiling of group members.
    Data were collected for all 106 stores belonging to national retail group, which sells
    three own retail brands. Some managerial implications were drawn.

    Keywords: Retail, supermarkets, sales, retail area, mixture regression models

    Affiliations:

    (1) Instituto Superior Técnico, Department of Civil Engineering and Architecture, Av. Rovisco Pais, 1049-
    001 Lisboa, Portugal, E-mail: abrochado@civil.ist.utl.pt

    (2) Universidade do Porto, Faculdade de Economia, Rua Dr. Roberto Frias
    4200-464 Porto, Portugal,E-mail: vmartins@fep.up.pt

    Specifics: poster presentation
  • Greedy Learning Algorithms and their Applications to Decision Trees

    Authors: Irad Ben-Gal and Niv Shkolnik (Tel-Aviv University, Tel-Aviv, Israel)
    Primary area of focus / application:
    Submitted at 10-Sep-2007 10:38 by
    Accepted
    In this paper we considered the problem of classification by decision trees. In order to
    better address the inherent tradeoff between optimality and complexity we implement
    a revised version of the LRTA*, a known artificial intelligence algorithm. We show
    that such implementation leads to appealing properties of the classification tree.
  • Kriging-Based Sequential Inspection Plans for Coordinate Measuring Machines

    Authors: P. Pedone, D. Romano and G. Vicario
    Primary area of focus / application:
    Submitted at 10-Sep-2007 10:46 by
    Accepted
    In the last two decades kriging models, originally developed for geological applications, have gained increasing popularity in Computer Experiments as a tool for producing accurate predictions of the output of a deterministic computer code. Going against the flow and back to the origins, the paper shows how kriging models may also be effective in a physical experimental setting. Exploiting their recognized prediction capability, we use them to build sequential experiments to be applied to an engineering problem: the construction of inspection plans for checking the compliance of industrial parts to dimensional and geometric specifications on Coordinate Measuring Machines. The inspection plan specifies which points are probed and in which order. Since the economy of the process forces the sample to be small, the engineering objective is to accurately estimate deviations from nominal dimensions and shape by probing a few points only. As best accuracy/cost trade-off is also the objective of sequential designs, the inspection plan will be treated as a sequential experiment to be designed on-line. In the paper we present a number of case-studies, related to the check of form tolerances (straightness, circularity), whose related form error depends heavily on the extreme values of shape deviations. So, in the construction of the sequential design we consider both informative (maximum prediction variance) and problem-specific (search for extreme deviations) criteria. Performance of kriging-based plans is compared with that of the simple non sequential ones massively used in industrial practice (uniform, random, stratified) and with deterministic sequential methods in the engineering literature.
  • A comparison between two methods for measuring uncertainty based on the ISO Guides

    Authors: L. Deldossi and D. Zappa (Cattolica University of Milan, Milan, Italy)
    Primary area of focus / application:
    Submitted at 10-Sep-2007 10:48 by
    Accepted
    In the last years the evaluation of the quality of the measurements is more and
    more frequently assessed by applying a new dedicated procedures defined in the ISO
    Guide (1995) - named Guide to the Uncertainty of the Measure (GUM) - based on the
    law of propagation of errors and on the Welch-Satterthwaite approximation. It is an
    alternative to the classical one defined in the ISO Guide 5725 (1994) based on the
    concept of repeatability and reproducibility obtained trough a variance component
    model.

    By means of some examples the two approaches are illustrated and compared to
    evaluate their limitations and their powers. Our proposal is to give some
    suggestions to the users about the method to be preferred according to their
    problem.

    The question it is becoming relevant because process variation is decreasing due to
    technological improvements, therefore the measurement procedure has to be adequate.
  • Safety Improvement Using DMAIC Algorithm

    Authors: Michal Tkác; and Marek Andrejkovic; (University of Economics Bratislava, Kosice, Slovak Republic)
    Primary area of focus / application:
    Submitted at 10-Sep-2007 11:09 by
    Accepted
    With this paper we intend to specify algorithm of realization and evaluation of safety improvement projects. We have used Six Sigma DMAIC methodology to solve the given, safety improvement problem. Individual stages of project realization are described in detail with designed methods, used in selected phases of the DMAIC. At the end of the paper, we present a case study from a realized safety improvement project in a U.S. company operating in metallurgical industry. In project realization, we have used methods like: integrated FMEA, expert opinion, statistical hypothesis testing, and computer simulations. At the end of the paper, we proposed how to evaluate safety improvement projects, using two criterions: technical and economical.

    KEY WORDS: Safety Improvement, Six Sigma, Expert Opinion, Project evaluation.
  • Managing Six Sigma projects - actively

    Authors: Michal Tkáč and Štefan Lyócsa (University of Economics Bratislava, Kosice, Slovak Republic)
    Primary area of focus / application:
    Submitted at 10-Sep-2007 11:10 by
    Accepted
    Using real options theory, we had modeled a decision process about quality improvement investments under uncertainty. We have created a generic model adapted to Six Sigma quality improvement methodology, which values the managerial flexibility of running improvement projects. By means of a case study, we have shown how to employ our model and have shown the differences compared to traditional valuation technique, the net present value. At the end of the paper, we have shortly discussed the possible implication of real options theory in regard to cost of quality models.

    KEY WORDS: Project management, Six Sigma quality improvement, Real options