Demagogue

Tim Harford seems to think so. At Slate.com, he writes:

Decades of economic studies have produced the conclusion that average wages increase with age almost until retirement, yet average productivity seems to be flat or perhaps even declining after the age of 50.

... I can look forward to a big bag of hate mail for reporting on this research, but I think that subconsciously we know it's true ...

The rest of the column is here.