There are four aggregate demand determinants that are grouped by the expenditure categories, such that: investment expenditures, consumption expenditures, net expenditures, government spending. Among these determinants, investment expenditure component seems to be the most erratic.
Investment expenditures are grouped in 5 categories as it follows: interest rates, expectations, physical wealth, technologies, capital prices.
The higher the interest rates are, the fewer investments are made and the aggregate demand decreases.
The capital price is also a determinant factor in investment expenditure because the more increased the price of capital is, the more decreased the investment expenditures and aggregate demand are.
New technologies are also a determinant factor that influences the investment expenditures, increasing them.
The boost of aggregate demand also occurs when the business sector identifies a future economical improvement and decides to increase the investments.
As a conclusion, the cyclical behavior of aggregate demand is given by the increased unpredictable conduct of investment expenditure component.