You're quite right; we would look at the cumulative amount of research over time. We look at the research stemming from the 1984 report, including the internal research report “Optimizing the Protection of School Bus Passengers”. That was from 2010, and it is now available on the department's website.
We look at other research as well, including a summary from 2007 of collision studies that occurred between 1995 and 2004. We would look at the totality of the research to inform the development of refinements and updates to Canada's motor vehicle safety standards as they apply to school buses.