In economics, distribution is the way total output, income, or wealth is distributed among individuals or among the factors of production (such as labour, land, and capital). In general theory and in for example the U.S. National Income and Product Accounts, each unit of output corresponds to a unit of income. One use of national accounts is for classifying factor incomes and measuring their respective shares, as in national Income. But, where focus is on income of persons or households, adjustments to the national accounts or other data sources are frequently used. Here, interest is often on the fraction of income going to the top (or bottom) x percent of households, the next x percent, and so forth (defined by equally spaced cut points, say quintiles), and on the factors that might affect them (globalization, tax policy, technology, etc.).