This is different from what we normally think of as investment in that we do not include money in a bank account, stocks and bonds, etc. We also do not count re-sales of existing physical assets.
Economist just count new, physical investments.
It excludes government transfer payments and is calculated before any deductions are taken for income taxes. Disposable Taxes symbolized by the letters DI the sum of the incomes that all individuals in the economy after all taxes have been deducted and all transfer payments have been added. Leakage the funds that leak out of the economy and depicts that we spend less than we earn. Savings and import spending make up the leakage. Transfer Payments the sums of money that the government gives certain individuals as grants rather than payments for services rendered to employers.