California Analysis
Data
The California collision dataset is from the California Highway Patrol - the California Statewide Integrated Traffic Record System (SWITRS). Traffic collision data from January 2015 to December 2018 contains 4,866,995 records.
Porportion by Month
Over the years, in California approximately 7.5% traffic collisions are caused by DUI. There is a slight decrease in the number of cases being recorded and the the general percentage over a month does not alter by more than 15%, which is relatively stable.
Linear Regression
To statistically assess the trend, we first applied linear regression on the monthly data. The coefficient of the slope is negative but it is approximately zero which indicates there is not a statistically significant change in the percentage of DUI cases before and after RML, which matches what we saw on the previous graph.