In
economics and
finance, an
index is a statistical measure of changes in a representative group of individual data points. These data may be derived from any number of sources, including company performance, prices, productivity, and employment. Economic indices track economic health from different perspectives. Influential global financial indices such as the
Global Dow, and the
NASDAQ Composite track the performance of selected large and powerful companies in order to evaluate and predict economic trends. The
Dow Jones Industrial Average and the
S&P 500 primarily track U.S. markets, though some legacy international companies are included. The
consumer price index tracks the variation in prices for different consumer goods and services over time in a constant geographical location, and is integral to calculations used to adjust salaries, bond interest rates, and tax thresholds for inflation. The
GDP Deflator Index, or real GDP, measures the level of prices of all new, domestically produced, final goods and services in an economy. Market performance indices include the
labour market index/
job index and proprietary
stock market index investment instruments offered by
brokerage houses.