Research Area

My areas of interest are Data Visualization, Multivariate Categorical Data Analysis, Statistical Computing, Exploratory Data Analysis and Interactive Statistical Graphics.

Software

• MANET. MANET is for exploring data, whether raw data, transformed data or model residuals. MANET provides a range of graphical tools specially designed for studying multivariate features. Anyone involved in analysing data will find MANET useful for gaining insights into the structure and relationships of their data sets.
  
• GGobi. GGobi is software for data exploration using highly interactive statistical graphics. My main contribution is a first implementation of area charts, such as barcharts and histograms.
  
• R packages/code.
  • Letter Value Boxplots (with Karen Kafadar, Hadley Wickham):
    allows one (and two) dimensional boxplots for large data sets based on the letter value statistics. Available on CRAN as package lvplots
    
  • Scagnostics for Projection Pursuit (with Lee Wilkinson, Hadley Wickham, Dianne Cook):
    graph-theoretic scatterplot diagnostics provide a set of indices for projection pursuit. Code is under development, will be made available on CRAN by the end of 2007.
    My routines are in files setup.R, anneal.R, and examples.R
    

Prizes

• Info Vis Contest 2005:"Boom and Bust of Technology Companies at the Turn of the 21st Century"
  with Hadley Wickham, Dianne Cook, Junjie Sun, Christian Röttger; our submission received a first prize and is now part of the Information Visualization Benchmarks Repository.
  
• ASA Data Expo 2006."Glaciers Melt as Mountains Warm"
  with Hadley Wickham, Jonathan Hobbs, Dianne Cook; our poster won the second prize.
  
• LAS Award for Early Excellence in Research/Creative Activity 2006
  

• Graphics of Large Datasets, with Antony Unwin and Martin Theus, Springer, New York, 2006.
  in amazon.com
• Graphical Tools for the Exploration of Multivariate Categorical Data, ISBN 3831116601, 2001.
  in Google Books
  

Refereed Publications:

Buja A., Swayne D.F., Littman M., Dean N., Hofmann H.: Interactive Data Visualization with Multidimensional Scaling tentatively accepted for publication in the Journal of Computational and Graphical Statistics (only minor fixes necessary).

Cook D., Hofmann H., Nikolau B., Wurtele E., Lee Eun-kyung, Yang H.: Exploring gene expressions using plots. Journal of Data Science, accepted, 2005.

Ahn J.S., Cook D., Hofmann H.: A Projection Pursuit Method on the multidimensional squared Contingency Table Computational Statistics, Vol 18 (4), pp. 605­626, 2003

Wurtele E.S., Dickerson J.D., Cook D., Hofmann H., Li J., Diao L.:MetNet: software to build and model the biogenetic lattice of Arabidopsis. Comparative and Functional Genomics. Vol 4, pp.239­245, 2003.

Hofmann H.: Constructing and reading mosaicplots Computational Statistics and Data Analysis, Vol 43, No. 4, pp. 565-580, 2003.

Unwin A., Hofmann H., Wilhelm A.: Direct Manipulation Graphics for Data Mining. International Journal of Image and Graphics, Vol. 2, No. 1, pp. 49-65, 2002.

Hofmann H.: Generalised Odds Ratios for Visual Modelling. In Journal of Computational and Graphical Statistics, 10, pp 628-640, 2002.

Hofmann H., Unwin A. Wilhelm A.: Data Mining and Statistics - Introduction. in Computational Statistics, 16(3),pp. 317-321, 2001.

Hofmann H., Wilhelm A.: Visual Comparisons of Association Rules. In Computational Statistics, 16(3), pp 399-416, 2001.

Wilhelm A., Hofmann H.: Graphics for Categorical Data and their Applications in Data Mining. In C. Provasi (Ed.), Modelli Complessi e Metodi Computazionali Intensivi per la Stima e la Previsione, pp. 51-56, 2001.

Hofmann H.: Exploring Categorical Data: Interactive Mosaic Plots. In Metrika, 51(1), 11-26, 2000.

Hofmann H., Theus M.: Selection Sequences in MANET. Computational Statistics, 13(1), 77-87, 1998.

Unwin A., Hawkins G., Hofmann H., Siegl B.: Interactive Graphics for Data Sets with Missing Values - MANET. Journal of Computational and Graphical Statistics, 5(2), pp. 113-122, 1996.

Refereed Conference Contributions:

Thostenson J., Lowell D., Schroeder D., Hofmann H.: Bootstrap Simulation Evaluations of Missing Data Methods Applied to Smoking Cessation Data. In ASA Proceedings, 2006.

Yakhnenko O., Hofmann H.: Exploring Parameters in Loglinear Models In ASA Proceedings, Section on Statistical Graphics, 2005.

Hofmann H.: Interactive biplots for visual model ling. in Proceedings in Computational Statistics 16th Symposium held in Prague, Czech Republic, Antoch, Jaromir (Ed.), pp. 235­250, 2004.

Lee E-K, Cook D, Hofmann H, Wurtele ES, Kim D, Kim J, and An H.: GENEGOBI : Visual data analysis tools for microarray data. in Proceedings in Computational Statistics 16th Symposium held in Prague, Czech Republic, Antoch, Jaromir (Ed.), 2004.

Theus M., Cook D., Hofmann H.: Scatterplots for Massive Datasets in Computing Science and Statistics, Vol 35 , 2003.

Zhang Jing, Miller L. Cook D., Hardjasamudra A., Hofmann H.: Densityplot Matrix Display for Large Distributed Data. In Proc. of the IEEE International Conference on Data Mining 2003.

DiBenedetto D., Hofmann H.: Mining with your Eyes. Thats Interactivity. In Proc. of the Meeting of the Societ`a Italiana di Statistica, 2003.

Hofmann H., Wilhelm A.: Exploring association rules by interactive graphics. In W. Gaul, G. Ritter (Eds.), Classification, Automation, and New Media, 181-188. Springer: Berlin, 2002.

Unwin A., Hofmann H., Bernt K.: Multiple Association Rules Control. In Proc. of the 5th European Conf. on Principles and Practice of Knowledge Discovery in Databases (PKDD’01), pp. 472­483, 2001.

Hofmann H., Siebes A., Wilhelm A.: Visualising Association Rules with Interactive Mosaic Plots. In Proc. of the 6th Int’l Conference of SigKDD, pp. 227-235, 2000.

Hofmann H.: Graphical Stability of Data Analysing Software. In R. Klar Opitz, O. (Ed.), Classi- fication and Knowledge Organisation, (pp. 36-43). Freiburg: Springer, 1997.