Explanation:

National Income (NI): Is also known as National Income at factor cost which means total income earned by resources for their contribution of land, labour, capital and organisational ability. Hence, the sum of the income received by factors of production in the form of rent, wages, interest and profit is called National Income. Symbolically, NI=NNP +Subsidies-Interest Taxes or, GNP-Depreciation +Subsidies-Indirect Taxes or, NI=C+G+I+(X-M) +NFIA-Depreciation-Indirect Taxes +Subsidies Personal Income (PI): Is the total money income received by individuals and households of a country from all possible sources before direct taxes. Therefore, personal income can be expressed as follows: PI=NI-Corporate Income Taxes-Undistributed Corporate Profits- Social Security Contribution +Transfer Payments. Disposable Income (DI) : It is the income left with the individuals after the payment of direct taxes from personal income. It is the actual income left for disposal or that can be spent for consumption by individuals. Thus, it can be expressed as: DI=PI-Direct Taxes Per Capita Income (PCI): Is calculated by dividing the national income of the country by the total population of a country. Thus, PCI=Total National Income/Total National Population