autism         		The data comes from researchers at the University of Michigan (Oti et al., 2006)
                        as part of a prospective longitudinal study of 214 children.

classroom               The Study of Instructional Improvement (SII; Hill, Rowan, and Ball, 2004) was carried 
                        out by researchers at the University of Michigan to study the math achievement scores 
                        of first- and third-grade students in randomly selected classrooms from a national U.S. 
                        sample of elementary schools.

rat.brain               The data used in this example were originally reported by Douglas, et al. (2004). 
                        The aim of their experiment was to examine nucleotide activation (guanine nucleotide bonding)
                        in seven different brain nuclei (i.e., brain regions) among five adult male rats.

ratpup         		The data come from a study in which 30 female rats were randomly assigned to receive 
                        one of three doses (High, Low, or Control) of an experimental compound.

veneer                  The Dental Veneer data were collected by researchers at the University of Michigan Dental 
                        School, in a study investigating the impact of veneer placement on subsequent gingival (gum)
                        health among adult patients (Ocampo, 2005). 
