Explain the main methods of investment appraisal, including payback, average rate of return and net present value, and evaluate their use in investment decisions

What this dot point is asking

SEAB wants you to explain and calculate the main investment-appraisal methods - payback, average rate of return (ARR), and net present value (NPV) - and to evaluate which a firm should use. The central concepts are the time value of money (which NPV captures and the others ignore) and the recognition that each method measures something different, so firms use them together alongside judgement.

The answer

Why appraise investments

Investment appraisal assesses whether a large, long-term investment (new machinery, a factory, a project) is financially worthwhile, by comparing the initial outlay with the expected future cash flows. It reduces the risk of committing large sums to poor projects.

Payback period

The payback period is the time taken for the project's net cash inflows to recover the initial outlay. Calculated by accumulating inflows until they equal the outlay (interpolating within the year).

• Strengths: simple, focuses on liquidity and risk (quicker payback = lower risk and faster cash recovery).
• Weaknesses: ignores all cash flows after payback, and ignores the time value of money.

Average rate of return (ARR)

The ARR expresses the average annual profit as a percentage of the initial outlay:

where average annual profit = (total inflows − initial outlay) ÷ project life.

• Strengths: measures profitability, easily compared to a target return or interest rate.
• Weaknesses: ignores the timing of cash flows and the time value of money; uses average profit, which can hide an uneven profile.

Net present value (NPV) and the time value of money

The time value of money is the principle that a sum now is worth more than the same sum later, because money now can be invested to earn a return (and because of inflation and risk). So future cash flows are discounted to their present value.

NPV discounts all future cash flows to their present value using the firm's cost of capital, then subtracts the initial outlay:

A positive NPV means the project adds value (returns more than the cost of capital) and should be accepted; a negative NPV means it does not.

• Strengths: accounts for the time value of money and the whole life of the project - the most complete, theoretically sound method.
• Weaknesses: more complex, and highly sensitive to the chosen discount rate and the cash-flow forecasts.

Evaluating: which method to use

No single method suffices because each measures something different - payback measures speed and risk, ARR measures average profitability, NPV measures value created allowing for timing. Firms therefore use them together, and the decision also depends on:

• The cost of capital (the discount rate and the hurdle for ARR/payback).
• Forecast reliability - all methods rest on uncertain future cash flows.
• Qualitative factors - strategic fit, risk, competitor response.
• Objectives - liquidity-focused or risk-averse firms weight payback; profitability-focused firms weight ARR or NPV.

The exam rewards calculating correctly, explaining each method's strengths and limits, favouring NPV on theory, and concluding that the methods are used together with judgement.

Examples in context

Example 1. Payback in fast-moving tech. Firms in rapidly changing technology markets often weight the payback period heavily, because cash-flow forecasts beyond a couple of years are highly uncertain and a quick recovery of the outlay limits risk if the market shifts. They may accept a project with a strong payback even when longer-term NPV is hard to estimate reliably - showing how a firm's emphasis among the methods reflects its risk and the predictability of its market.

Example 2. NPV for major infrastructure in Singapore. Large, long-lived investments - a new plant, port facilities or transport infrastructure - generate cash over many years, so appraisers in Singapore and elsewhere rely on NPV to discount those distant cash flows to today's value at an appropriate cost of capital. Because timing matters enormously over decades, NPV is the decisive method for such projects, while payback and ARR serve as supporting checks - illustrating method choice driven by the project's time horizon.

Try this

Q1. State one strength and one weakness of the payback method. [2 marks]

• Cue. Strength: it is simple to calculate and focuses on how quickly the outlay is recovered, which matters for liquidity and risk. Weakness: it ignores all cash flows after the payback point and ignores the time value of money.

Q2. A project costs \150{,}000 and returns net inflows of \50{,}000, \60{,}000 and \70{,}000 over three years. Calculate the average rate of return. [3 marks]

• Cue. Total inflows = 50+60+70 = \180{,}000$; total profit$= 180{,}000 - 150{,}000 = \$30{,}000$; average annual profit = 30{,}000 / 3 = \10{,}000$. ARR$= \dfrac{10{,}000}{150{,}000} \times 100 = 6.67%$.

Q3. Analyse why a firm should not base a major investment decision on the numerical appraisal alone. [6 marks]

• Cue. All appraisal methods rest on forecast future cash flows that are uncertain, and on assumptions such as the discount rate, so a small forecasting error can flip the result - the numbers are only as good as their inputs. Each method also captures something different and has blind spots (payback ignores later cash flows and timing; ARR ignores timing; NPV depends heavily on the discount rate). Crucially, the appraisal ignores qualitative factors that can be decisive: strategic fit with the firm's objectives, the risk and reversibility of the project, competitor and market responses, and the firm's cash position and appetite for risk. So a firm should treat the appraisal as one important input, use the methods together, test the sensitivity of the result to its assumptions, and combine it with strategic judgement rather than deciding on a single computed figure.