Except we can look at the price of computers, milk, eggs, oil, etc. etc.

ftp://ftp.bls.gov/pub/special.requests/cpi/cpiai.txt

Across all of our goods, the total change (ie: CPI) between January 2013 and Febuary 2013 changed from 230.280USD to 232.166USD. A difference of 0.8%

In the same period, BTC changed from 13.51 to 20.41, a difference of 51.1%

It's common to value a currency against a basket of other currencies; you would still see BTC's volatility be huge.

Because of currency manipulation, some would rather think of bitcoin's value with respect to a basket of commodities instead of currencies.