"According to the formula, COLAs are based on increases ... While the market basket used to calculate CPI measures the prices of items, it does not measure how quality can change over time.

The formula for calculating savings account interest uses the initial deposit, the annual interest rate and the years of growth. Compound interest earns the account holder more than simple ...

Conversely, the PPI includes export prices while the CPI does not. The BLS produces more than 10,000 product and industry price indexes each month, which it then uses to calculate the PPI.