A school district is interested in
comparing two driver education curricula, called the ``Safe
performace curriculum'' (SPC) and the ``Pre-driver licensing
curriculum'' (PDLC). In particular, they want to know if students
who participated in SPC were less likely to have a collision than
students who participated in PDLC. Three high schools offered both
curricula during one year. 300 students who wanted driver education
(100 from each school) were assigned to one of SPC or PDLC (roughly
half and half). Gender, grade point average (0.0 to 4.0), school (1,
2, or 3), and curriculum (SPC or PDLC) were recorded at the
beginning of the driver education. One year after completion of the
education, students were asked if they had had a collision
(yes/no) in the past year. They were asked again two years after 
completion and three years after completion.

These data are courtesy of Dr. Marie Davidian at NC State University.