Compared both the NTSI Level I and Level II programs with appropriate control groups of drivers who were eligible and motivated to take the NTSI program in Santa Clara County, California, but had their tickets dismissed without participating in the program. This research is one of the most valid studies of Traffic Violator Schools that has been produced. It has a valid control group selected from the same population of drivers as the treatment group. It uses objective state-reported data. No differential attrition is permitted between treatment and control.
Sample size is adequate to capture the overall effect of the program in reducing violations.
Subjects were assigned to the correct conditions in a careful procedure controlled by the experimenter. This is the largest study of its kind to use a scientifically valid research design. I course, the data indicates that the NTSI program appears to lessen the chance of recidivism. For the Level II course, the data indicate that the impact of the Level II program on subsequent accidents is quite dramatic. This is statistically significant well beyond the .05 level.