When you have bivariate data – that is, data on two variables – either or both may be categorical or continuous. When there is one of each, and you want to compare the distribution of one across levels of the other, a parallel box plot is a good option. Suppose, for example, you want to compare the heights of people across ethnic groups. Read more!
Regression to the mean is a well known statistical artifact affecting correlated data that is not perfectly correlated. It was first noticed by Sir Francis Galton in the late 19th century. He noted that the tallest fathers will have sons who are not as tall, and, similarly, the shortest fathers will have sons who are not as short. But this is true, not because of any general tendency toward mediocrity: Indeed, the range of heights of people shows no signs of diminishing. How can this be? Read more!
This is a talk developed by David Cassell and me, and given at NESUG and SGF and WUSS
I specialize in helping graduate students and researchers in psychology, education, economics and the social sciences with all aspects of statistical analysis. Many new and relatively uncommon statistical techniques are available, and these may widen the field of hypotheses you can investigate. Graphical techniques are often misapplied, but, done correctly, they can summarize a great deal of information in a single figure. I can help with writing papers, writing grant applications, and doing analysis for grants and research.
Specialties: Regression, logistic regression, cluster analysis, statistical graphics, quantile regression.