Accelerator effect

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The accelerator effect in economics is a positive effect on private fixed investment of the growth of the market economy (measured e.g. by a change in gross domestic product (GDP)). Rising GDP (an economic boom or prosperity) implies that businesses in general see rising profits, increased sales and cash flow, and greater use of existing capacity. This usually implies that profit expectations and business confidence rise, encouraging businesses to build more factories and other buildings and to install more machinery. (This expenditure is called fixed investment.) This may lead to further growth of the economy through the stimulation of consumer incomes and purchases, i.e., via the multiplier effect.

In essence, the accelerator effect proposes that investment levels are contingent on the pace of change in GDP rather than its absolute level. In simpler terms, it is the acceleration or deceleration of economic growth that shapes businesses' choices regarding investments.^[1]

The accelerator effect operates in reverse as well: when the GDP declines (entering a recession), it negatively impacts business profits, sales, cash flow, capacity utilization, and expectations. Consequently, these factors discourage businesses from making fixed investments, which further intensifies the recession due to the multiplier effect.^[2]

The accelerator effect fits the behavior of an economy best when either the economy is moving away from full employment or when it is already below that level of production. This is because high levels of aggregate demand hit against the limits set by the existing labour force, the existing stock of capital goods, the availability of natural resources, and the technical ability of an economy to convert inputs into products.