Also, the CPI makes comparison between years other than the base year easy because the types and quantities of the goods and services consumed are fixed. The IPD is based on current economic conditions and consumer expenditures, tastes and preferences. It is frequently used to adjust state economic and revenue data. The state expenditure limit is based on the IPD as well as inflation adjustments in the state's biennial budget. There are no inflation indexes for the state of Washington.
Indexes also are available within each region, cross-classified by area population size.
For the Northeast and West, however, indexes for non-metropolitan areas are not available. BLS also publishes indexes for 26 local areas. Local area indexes are byproducts of the national CPI program. Each local index has a much smaller sample size than the national or regional indexes, and is, therefore, subject to substantially more sampling and other measurement error. As a result, local area indexes are more volatile than the national and regional indexes.