Your Dec. 11 editorial (“Our View: Blanket limits on license renewals not the way to cut senior driver risk”) was a helpful description of the complicated issues faced by the Bureau of Motor Vehicles, senior drivers and their families. However, it overstates the magnitude of the problem.

The way one measures outcomes makes a big difference in how senior drivers (generally over 70) compare to teenage ones: crashes or fatalities, by driver or by estimated 100,000 miles driven. Both national and Maine data consistently show crash rates per driver for seniors into their 90s insignificantly different from middle-aged drivers – 1½ to three times higher – while teen drivers are over six times higher. But fatalities per driver do jump markedly after age 75, and by 90 approach the fatality rates seen in 16-year-olds.

However, the old and very old’s frailty plays a larger and larger role in these fatalities; crashes of similar severity are more likely to kill a senior over 75 and/or his peer age passengers than a teenager and his companions. Most studies estimate this frailty effect of aging accounts for 50 to 75 percent or more of the increased fatality rate for the elderly driver. And better car and traffic design are also helping all age groups dramatically.

But senior driving issues are significant, especially for the drivers themselves. Self and family identification, policy changes, community reporting and public transportation all need to be beefed up, as the editorial suggests.