Prof Nelmarie Louw

Associate Professor

University of Stellenbosch

Private Bag X1, Matieland

7602, South Africa

Tel:         +(27) 21 808 3977

Fax:        +(27) 21 808 3830

e-mail:     nlouw@sun.ac.za

Obtained a Ph.D in 1997 at the University of Stellenbosch in the Department of Statistics and Actuarial Science. Title of thesis: "Aspects of the Pre- and Post-Selection Classification Performance of Discriminant Analysis and Logistic Regression", with promoters professors Niel le Roux and Sarel Steel.

Present Research Interests

Discriminant Analysis and Classification, Outlier Identification, Kernel Methods for classification, Variable Selection and Dimension Reduction.

Present Teaching Subjects

Probability Theory and Statistics 144

Mathematical Statistics 214

Bootstrap Techniques (post-graduate)

Publications in Journals

• Le Roux, N.J.; Steel, S.J. and Louw, N.  (1997).  "Variable selection and error rate estimation in discriminant analysis."  Journal of Statistical Computation and Simulation, 59, 195-219. 

• Louw, N.; Steel, S.J. and Le Roux, N.J.  (1998).  "A comparison of the classification performance of two approaches to polychotomous logistic regression."  South African Statistical Journal,  32, 27-50. 

• Steel, S.J.; Louw, N. and Le Roux, N.J.  (2000).  "A comparison of the post selection error rate behaviour of the normal and quadratic linear discriminant rules." Journal of Statistical Computation and Simulation, 65, 175-172. 

• Steel, S.J. and Louw, N.  (2001).  "Variable selection in discriminant analysis: measuring the influence of individual cases."  Computational Statistics and Data Analysis, 37, 249-260.

• Steel, S.J. and Louw, N. (2002).  “An integrated approach to outlier identification and variable selection in discriminant analysis.”  South African Statistical Journal  36, 129-151.

• Steel, S.J. and Louw, N. (2003).  “Improving the classification performance of a discriminant rule by dealing with influential cases.” Studies in Classification, Data Analysis and Knowledge Organization , 109-117.

• Louw, N. and Steel, S.J.  (2005).  “A review of kernel Fisher discriminant analysis for statistical classification.”  South African Statistical Journal  39, 1-21.

• Louw, N and Steel, S.J. (2006).  “Variable selection in kernel Fisher discriminant analysis by means of recursive feature elimination.”   Computational Statistics and Data Analysis 51, 2043-2055.

• Louw, N and Steel, S.J. (2006).  “Input variable selection in kernel Fisher discriminant analysis.”   Studies in Classification, Data Analysis and Knowledge Organization, 126-133.

• Louw, N,  Lamont, MMC & Steel, SJ. (2008). “Identification of Influential Cases in Kernel Fisher Discriminant Analysis”.  Communications in Statistics - Simulation and Computation, 37, 2050-2062.
• Louw, N,  Lamont, MMC & Steel, SJ. (2010). “Identifying Influential Cases in Kernel Fisher Discriminant Analysis by using the smallest enclosing Hypershere”.  Studies in Classification, Data Analysis and Knowledge Organization, 363-371.
• Steel, SJ, Louw, N  & Bierman, S. (2011).  “Variable Selection for Kernel Classification”. Communications in Statistics - Simulation and Computation, 40, 229-246.

   

International Conferences

• Louw, N.; Steel, S.J. and Le Roux, N.J.  (1996).  "Selection of variables in discriminant analysis by means of cross model validation."  Sydney International Statistical Congress, Sydney, Australia. 

• Louw, N.; Steel, S.J. and Le Roux, N.J.  (1997).  "Pre-test variable selection in discriminant analysis."  The Second Scandinavian-Ukrainian Conference in Mathematical Statistics, Umea, Sweden. 

• Louw, N.; Steel, S.J. and Le Roux, N.J.  (1998).  "Variable selection and error rate estimation in normal linear and quadratic discriminant analysis."  The Sixth Conference of the International Federation of Classification Societies, Rome, Italy. 

• Steel, S.J. and Louw, N.  (1999).  "Selection influential points in a financial classification problem."  14th International Workshop on Statistical Modelling, Graz, Austria. 

• Steel, S.J. and Louw, N. (2000). "Variable selection in discriminant analysis: measuring the influence of individual cases."  15th International Workshop on Statistical Modelling, Bilbao, Spain. 

• Louw, N. and Steel, S.J. (2001).  “Variable selection in discriminant analysis in the presence of outliers.  23^rd International Conference on Information Technology Interfaces.  Pula, Croatia.

• Steel, S.J. en Louw, N. (2002).  “Improving the classification performance of a discriminant rule by dealing with influential cases. ” 26th Annual Conference of the Gesellschaft für Klassifikation, Mannheim, Germany.

• Louw, N. and Steel, S.J.  (2004).  “Application of alignment in kernel Fisher discriminant analysis to identify important input variables.”  19^th International Workshop on Statistical Modelling, Florence, Italy.

• Steel, S.J. and Louw, N.  2005.  “Input variable selection in kernel Fisher discriminant analysis.”  The 29^th Annual Conference of the Gesellschaft für Klassifikation, Magdeburg, Germany.

• Louw, N and Steel, S.J. 2005.  “Variable selection in kernel Fisher discriminant analysis by means of recursive feature elimination.”  The 5^th Scientific Meeting of the Classification and Data Analysis Group of the Italian Statistical Society, Parma, Italy.

• Louw, N,  Lamont M.M.C and Steel, S.J. 2006.  “Outlier identification in kernel Fisher discriminant analysis.”  26^th European Meeting of Statisticians, Torun, Poland.

• Steel, S.J, Oosthuizen, S and Louw, N.  2006.  “A framework for input variable selection in kernel methods.”  26^th European Meeting of Statisticians, Torun, Poland.

• Louw, N. Lamont M.M.C and Steel, S.J. 2007.  “Identification of atypical cases in kernel Fisher discriminant analysis”.  S.Co 2007 conference, Venice, Italy.

• Louw, N. Lamont M.M.C and Steel, S.J. 2008.  “Identifying atypical cases in kernel Fisher discriminant by means of the smallest enclosing hypersphere”.    The 32^nd Annual Conference of the Gesellschaft für Klassifikation, Hamburg, Germany.

• Louw, N. and Lamont M.M.C. 2009.  “Robust kernel Fisher discriminant analysis”.  The International Conference on Robust Statistics, Parma Italy.

• Louw, N. 2010.  “Kernel Fisher Discriminant Analysis with robust Kernels”.  The International Conference on Robust Statistics, Prague, Czech Republic.

• Louw, N. 2010.  “Robust Kernel Fisher Discriminant Analysis with weighted Kernels”.  Joint meeting of the Classification and Data Analysis Group of the Italian Statistical Society and the Gesellschaft für Klassifikation, Florence, Italy.

• Louw, N and Wilken, R. 2011. “Kernel based Dimension Reduction and Classification of Near Infrared Spectroscopy Data”. 14th Applied Stochastic Models and Data Analysis International Conference, Rome, Italy.

   

   

National Conferences (South African)

• Louw, N. and Le Roux, N.J. (1995).  "A comparison of linear discriminant analysis and logistic regression."  Annual Conference of the South African Statistical Association,  University of the Free State. 

• Steel, S.J.; Louw, N. and Le Roux, N.J.  (1996).  "Pre-test type variable selection in discriminant analysis."  Annual Conference of the South African Statistical Association,  University of Stellenbosch. 

• Louw, N.; Steel, S.J. and Le Roux, N.J.  (1996).  "Variable selection and error rate estimation in discriminant analysis by means of cross model validation."  Annual Conference of the South African Statistical Association,  University of Stellenbosch. 

• Louw, N.; Steel, S.J. and Le Roux, N.J.  (1997).  "A comparison of the classification performance of two approaches to polychotomous logistic regression."  Annual Conference of the South African Statistical Association, Dikhololo. 

• Louw, N. and Steel, S.J. (2001).  "An integrated approach to variable selection and outlier detection in discriminant analysis.  Annual Conference of the South African Statistical Association, Goudini.

• Louw, N. and Steel, S.J.  (2003).   “A comparison of the classification performance of Fisher's linear discriminant rule and kernel Fisher discriminant analysis.” 50^th Annual Conference of the South African Statistical Association, Johannesburg.

• Louw, N, Lamont M.M.C and Steel, S.J. 2006.   Identification of influential cases in kernel Fisher discriminant analysis. Annual Conference of the South African Statistical Association, Stellenbosch.

• Lamont M.M.C, Louw, N and Steel, S.J. 2006.  The effect of outliers on the performance of kernel Fisher discriminant analysis.  Annual Conference of the South African Statistical Association, Stellenbosch.

Societies and Committees

Member of the South African Statistical Association.

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