I.I.I. chief actuary James Lynch digs into the data in an informative piece on loss trend factors:
Actuaries can be buggy about numbers, to say the least, and my article in this month’s Actuarial Review — a publication of the Casualty Actuarial Society (CAS) – looks at a couple of sources of loss trends that can act as useful benchmarks.
One looks at workers compensation medical costs in 25 states. It is produced by the Workers Compensation Research Institute (WCRI), an organization I work closely with in my role as I.I.I. chief actuary.
The other looks at comp loss trends plus those of about a dozen other lines of business and has information going back to the 1930s, if you do a little digging. Older actuaries remember it as the Masterson Index, named after a Stevens Point, Wisconsin, actuary who created it and maintained it until relatively recently. Now Towers Watson actuaries have taken over the calculation.
As a sidebar, I also looked at the way the federal government measures auto inflation, including how it handles the introduction of predictive models and other overhauls to rating plans.