1. A Comparison of the Outlier Detecting Methods: An Application on Turkish Foreign Trade Data

    Dr. Aylin KOLBAŞI1, Prof. Dr. Aydın ÜNSAL2

    1.Turkish Statistical Office, Ankara/Türkiye.
    2.Hacı Bayram Veli Unıversity, Ankara/Türkiye.

    Abstract: In many data analysis tasks a large number of variables are being recorded or sampled. One of the first steps in obtaining a consistent analysis is to identify observations that are far from the center. Outlier values often carry important information, even if they are considered to be errors or problems. However detected outliers lead to incorrect modeling, biased parameter estimates, and incorrect results. For this reason, it is very important to identify them before modeling and analyzing. In this study it has been tryied to determine the method of detecting outliers which can detect the outliers in foreign trade data in the most accurate way. For this, z-score, median z-score, box-plot, adjusted box-plot, B-H method, k-means clustering method and robust regression methods were applied to the foreign trade data set and the application results of outlier detection methods were compared by considering some criteria. In the light of these criteria, the most appropriate outlier detection methods that can be applied to the foreign trade data set have been determined.

    Keywords: Outlier, foreign trade, outlier detection methods.

    Pages: 213 – 234 | Full PDF Paper
  2. A Validation for Dirichlet Problem

    Ummu Sahin Sener1, Ersin Sener2*

    1. Department of Mathematics, Kirklareli University, Kayali Campus, 39000, Kirklareli, Turkey.
    2. Department of Mathematics, Yildiz Technical University, Esenler, 34220, Istanbul, Turkey.

    Abstract: Euler method is often referred method because of ease of use and usefulness for ordinary differential equation. Usefulness is arises from simplicity and error analyses comfortableness. It is convenient for a second order differential equation because of reducibility. It is also used for Dirichlet problem. Analytical solution is compared with numerical approach. Analytical solution, numerical approach and error analyses are together reconfigured. Analytical solution is done Evolutionary Approach to Electromagnetics’ frame. Despite the fact that the approach is to be required solution of Klein-Gordon equation, it is just validated with 0.02 step Dirichlet problems’ numerical approach and analytical solution.

    Keywords: Dirichlet boundary-value problem, analytical solution, numerical solution, Maxwell equations, TM time-domain mode.

    Pages: 235 – 242 | Full PDF Paper