Automated Visualization and Analysis Using the Grammar of Graphics Foundation

by Leland Wilkinson

Systat Software Inc. & University of Illinois at Chicago

Date

Friday, October 16, 2009

Time

3:00 p.m. — 4:00 p.m.

Place

Informatics East, Rm. 130

Abstract: Visualization has at least three purposes: 1) the inspection of raw data, 2) the assessment of assumptions underlying fitted models, 3) the presentation of fitted models. Automated visualization (AV) is an attempt to serve these purposes through intelligent automation of visualization and analytic methods. While AV might be designed to serve all three purposes equally well, its most suitable applications involve the early stages of a discovery process. AV, however sophisticated, should not replace the interactive process underlying the development and fitting of models themselves. It is best suited for discerning missing values, irregularities, anomalies, coding errors, and other effects that might bias the fitting of models or refinement of judgments based on data.

The Grammar of Graphics is the title of a book and a framework for developing intelligent visualizations of statistical and scientific data. Joint work with Graham Wills, Dan Rope, and others has led to the implementation of a scalable visualization library based on the book. And joint work with Anushka Anand and Robert Grossman at UIC has led to the development of a novel algorithm (originally proposed by John Tukey) for detecting patterns in high-dimensional datasets. These ideas will be illustrated on real data through several different interactive software applications.

Biography: Wilkinson wrote SYSTAT, a statistical software package, in the early 1980's. This program was noted for its comprehensive graphics, including the first software implementation of the heatmap display now widely used among biologists. After his company grew to 50 employees, he sold it to SPSS in 1995. At SPSS, he assembled a team of graphics programmers who developed the nViZn platform that produces the visualizations in SPSS, Clementine, and other analytics products. The nViZn platform was modeled after Wilkinson's book on statistical graphics, The Grammar of Graphics. This book also influenced the development of the R (programming language) ggplot2 package and the Polaris project at Stanford. Wilkinson now serves as Executive VP of SYSTAT Software Inc. in Chicago.

Colloquium Provided By:

the School of Informatics