Net investment = gross investment minus replacement investment required to replace obsolete capital. The level of net investment tells us what is happening to the stock of fixed capital
Gross fixed investment is spending on fixed assets including buildings, plant and vehicles
Factors that affect investment demand
Profit-seeking businesses will be prepared to go ahead with an investment if they believe that it will - over its projected lifetime - yield a real rate of return greater than if the money had been invested in the next best alternative way. Opportunity cost is a useful idea to use here.
Private sector businesses usually focus on these objectives when investing in new capital inputs:
Improving productivity / efficiency to drive down unit costs and achieving economies of scale
Investing in capital embodies the most recent technological improvements
Expanding capacity to meet rising actual demand and to supply to new markets (e.g. exports)
Increasing capacity in advance of an expected increase in market demand (i.e. the accelerator)
Replacing obsolete capital equipment and buildings
Social cost benefit analysis
For government sector investment such as new roads, schools and prisons, priorities may be subtly different. Public sector capital projects are still subject to tests about their expected rates of return and the cost-benefitanalysis will include estimates of the social costs and benefits of the investment rather than a narrow focus on private costs and benefits.
Returns to an investment project
The expected returns from capital investment are determined by the demand for and the price of the output generated by an investment and by the costs of production
A rise in demand will increase the revenue streams that a business can expect from a new project
A change in the costs of purchasing capital inputs the costs of training workers to use new capital and in maintaining the capital stock will impact on the expected rate of return
For the UK, recent evidence suggests that the demand for new capital goods is interest rate inelastic. Partly this is because many firms prefer to use the capital market through the issue of new shares and bonds to raise funds for investment rather than relying on bank loans.
But the rate of interest can and does affect capital investment decisions – perhaps through its effect on confidence and also expectations of changing demand and the links between interest rates and the exchange rate.
Accelerator theories assume that for a business there is a desired capital stock for a given level of output and interest rates. A rise in output or a fall in demand may prompt increased levels of investment as firms adjust to reach the new optimal capital stock level
The accelerator model works on the basis of a fixed capital to output ratio. For example if demand in a given year rises by £4 million and each extra £1 of output requires an average of £3 of capital inputs to produce this output, then the net level of investment required will be £12 million
Consider the diagram below that shows an outward shift of AD that then causes an expansion of production, higher profits and prompts an increase in planned investment at each rate of interest. This boost in demand and output is said to bring about a positive ‘accelerator effect’
One criticism of this simple accelerator model is that the capital stock of a business can rarely be adjusted immediately to its desired level because of ‘adjustment costs’ and ‘time lags’. The adjustment costs include the cost of lost business due to installation of new equipment or the financial cost of re-training workers.
Firms will usually make progress towards achieving an optimum capital stock rather than moving smoothly to a new optimal size of plant and machinery. The time lags might be caused by supply-bottlenecks in industries that manufacture buildings and items of capital equipment and technology.
A further criticism of the accelerator model is that it ignores the spare capacity that a business might have at their disposal. At the end of a recession, businesses are operating below capacity limits and if demand then picks up in the recovery, they make more intensive use of existing capacity.
Business profits play an important role in allocating resources – for example, higher profits provide the funds for capital investment and also for research and development projects
Profits tend to follow a cyclical pattern – they fall during a recession or an economic slowdown. And they recover during phases of stronger economic growth