The document discusses various measures of inflation and cost of living. The consumer price index (CPI) measures the cost of typical household purchases and is used to track inflation. However, the CPI has limitations and may overstate inflation by about 1% annually due to substitution effects, new products, and unmeasured quality changes. The GDP deflator similarly measures price changes but for all goods and services produced rather than consumed. Price indexes are necessary to correct dollar amounts for inflation when making comparisons over time or calculating real interest rates.