Drunk Driving Fatalities and Population Change

with citations

The simplest explanation is usually best, and it is for that reason that the 21 year-old drinking age is often cited as the cause for the decrease in drunken driving fatalities. But suppose that there was an even more simple explanation for this change. Our analysis suggests there is: Population Change.

To state that the actual size of the population within a particular age range is the same from year to year is to state the obvious. Birth rates rise and fall over time. Each year, everyone is one year older. This year’s 18 year-old is next year’s 19 year-old. Because there is not the same number of births each year, the size of an age group varies each year. If we look at the number of underage lives “saved” relative to the size of that population as a whole it is clear that there were fewer drunken driving fatalities not because of changed law, but simply because there were fewer individuals between 16-20. In what may be the most fundamental critique of the argument that the 21 year-old drinking age has saved thousands of lives, our analysis shows that the number of drunken driving fatalities for both legal drinkers and underage drinkers closely tracks the population of that group over the period of time that the law’s effects were supposed to have taken place.

Population change and drunken driving fatalities:

populationchange.gif