Study	Reason for exclusion
Dreyer 1979	Lack of a no‐intervention group.
Gregersen 1994	This study compared professional driver education versus no professional driver education (i.e private instruction from parents etc) in 1,894 Swedish teenagers who had yet to obtain a driving license. The study was excluded because allocation of participants was not random. Page 455: "The division could not be made strictly on a random basis since the experimental group was to attend driving schools, and it was necessary to reduce the geographical distance to the schools as much as possible. In certain small villages, all of those within the sample were picked for the experimental group."
Planek 1974	Lack of a no‐intervention group.
Raymond 1973	Intervention and control groups were not selected by random allocation.
Schuman 1971	All participants were licensed drivers.
Schupack 1975	All participants were licensed drivers.