A 2001 report in the American Journal of Public Health selected 24 intersections that were converted into roundabouts in 8 different states, and analyzed the before and after crash data. In most cases, the time period (in months) was the same in the before and after periods; where it was not, the Bayes method was used for normalization. Researchers found that, overall, roundabouts reduce all crashes by 38% and reduce injuries by a whopping 76%.