"Inflation, as reported by the Consumer Price Index (CPI) is understated by roughly 7% per year...
The Boskin/Greenspan argument was that when steak got too expensive, the consumer would substitute hamburger for the steak, and that the inflation measure should reflect the costs tied to buying hamburger versus steak, instead of steak versus steak. Of course, replacing hamburger for steak in the calculations would reduce the inflation rate, but it represented the rate of inflation in terms of maintaining a declining standard of living. Cost of living was being replaced by the cost of survival...
Aside from the changed weighting, the average person also tends to sense higher inflation than is reported by the BLS, because of hedonics, as in hedonism. Hedonics adjusts the prices of goods for the increased pleasure the consumer derives from them. That new washing machine you bought did not cost you 20% more than it would have cost you last year, because you got an offsetting 20% increase in the pleasure you derive from pushing its new electronic control buttons instead of turning that old noisy dial, according to the BLS...
Then there is "intervention analysis" in the seasonal adjustment process, when a commodity, like gasoline, goes through violent price swings. Intervention analysis is done to tone down the volatility. As a result, somehow, rising gasoline prices never seem to get fully reflected in the CPI, but the declining prices sure do."
http://www.shadowstats.com/cgi-bin/sgs/article/id=343