Income and fertility
Gross domestic product (GDP) is the total dollar value of all goods an economy produces over a given time, usually expressed as a comparison to the previous quarter or year. If the year to year GDP is up 5 percent, then the economy has grown 5 percent. There are two approaches - the income approach (adding up all earnings over a year) and the expenditures approach (adding up what everyone spent). The income approach is described as the total employee compensation, gross profit for corporations and non-incorporated firms, and taxes minus subsidies. The expenditures method is more common and it specifically combines total consumption within households, and the total investment within a business. It also reveals how much money the government is spending and the balance of trade. Another factor by which is not promptly supportive are the youngsters who play a role within GDP. They clearly do not add to it and do not help the stock and bond market returns. Youngsters are wellsprings of advancement, entrepreneurial souls and play a major incentive to GDP.
Penn World Table
The Penn World Table (PWT) is a set of national-accounts data developed and maintained by scholars at the University of California, Davis and the Groningen Growth Development Centre of the University of Groningen to measure real GDP across countries and over time. Successive updates have added countries (currently 167), years (1950-2014), and data on capital, productivity, employment and population. The current version of the database, version 9, thus allows for comparisons of relative GDP per capita, as a measure of standard of living, the productive capacity of economies and their productivity level. Compared to other databases, such as the World Bank's World Development Indicators, the time period covered is larger and there is more data that is useful for comparing productivity across countries and over time.