Institute for Social Research Statistical Consulting Service

Lecture Outline

1. Failures to screen data
2. Assessing univariate problems
   • Boxplots and outliers
   • Transformations to symmetry
   • Normal probability plots
3. Assessing bivariate problems
   • Enhanced scatterplots
   • Smoothing relations
   • Transformations to linearity - resitstant lines, Box-Cox
   • Dealing with heteroscedasticity
4. Assessing multivariate problems
   • Multivariate normality
   • Outliers: univariate, bivariate, multivariate
   • Robust outlier detection
5. Dealing with missing data
   • Strategies for missing data
   • Simple imputation
   • Multiple imputation
6. SAS macro programs, from SAS System for Statistical Graphics (Friendly, 1991):
   • http://www.math.yorku.ca/SCS/sssg/
   • http://www.math.yorku.ca/SCS/sasmac/
7. Visualizing Categorical Data (Friendly, 2000):
   • http://www.math.yorku.ca/SCS/vcd/