Definition and Measurement (CPI)
The inflation rate measures the rate of increase in the general price level over a given period. A common measurement is the year-over-year change in the Consumer Price Index (CPI), which tracks price movements of a representative basket of goods and services. In Japan, the index that excludes fresh food is called core CPI, and the index that excludes both fresh food and energy is called core-core CPI; both remove volatile items to show the underlying price trend.
Nominal vs. Real Income
Nominal income is the face-value amount, while real income adjusts for inflation to reflect actual purchasing power. If your salary rises 3% but inflation is 5%, your real purchasing power has declined by about 2%. Using real values allows international and historical income comparisons to be made in purchasing-power terms.
Winners and Losers from Inflation
When a loan carries a fixed rate, inflation lightens the real repayment burden for the borrower and lowers the real value of what the lender receives. Mortgage debt shrinks in real terms, while savings lose value. Workers whose wages lag behind price increases become effectively poorer.
Assets such as real estate or equities can move in nominal price along with the price level, while cash and fixed-rate bonds lose value in real terms. Through these differences, inflation works as a redistribution of real income and wealth.
Impact on Rankings
World income rankings typically adjust for price levels through mechanisms such as PPP conversion, but in countries experiencing rapid inflation, data freshness affects results. Where prices rise quickly, even six-month-old data may diverge from current reality.