In our book, we discuss the important question of how to assign different parameterizations to categorical variables when fitting models (section 3.1.3). We show code in R for use in the lm() function, as follows:lm(y ~ x, contrasts=list(x,"contr.trea...

..often needed when preparing data for analysis (and usually forgotten until I need it for the next time).With the below code I convert a set of variables to factors - it could be that there are slicker ways to do it (if you know one let me know!) __ da...

Some people use both SAS and R in their daily work. They might be more familiar with SAS as a tool for manipulating data and R preferable for plotting purposes. While our goal in the book is to enable people to avoid having to switch back and forth, ...