why does the government calculate gdp
The data-point at issue in both cases is gross domestic product, or GDP, the total value of all goods and services produced within an economy each year. GDP is of critical economic importance; thousands of economists use estimates of the total amount spent or (equivalently) earned each year in their research. Governments also rely heavily on the figure, to shape policy or determine how much public spending is affordable. Yet GDP seems an impossibly complex thing to measure in a modern economy.