1.    Net Present Value (NPV)

        This is defined mathematically as the present value of cashflow less the initial outflow.

        Where    Ct is the cashflow
                       K is the opportunity cost of capital
                       Io is the initial cash outflow
                       n is the useful life of the project

        Decision Rule using NPV

        The decision rule under NPV is to:

        -    Accept the project if the NPV is positive
        -    Reject the project if NPV is negative

        Note: if the NPV = 0, use other methods to make the decision.

    2.    Internal Rate of Return (IRR)

        The internal rate of return of a project is that rate of return at which the projects NPV = 0

        Therefore IRR occurs where:


        Where r = internal rate of return

        Note that IRR is that ratio of return that causes the present value of cashflows to be equal to the initial cash outflow.

        Decision Rule under IRR

        If IRR > opportunity cost of capital - accept the project

        -    IRR < opportunity cost of capital - reject the project

        -    IRR = opportunity cost of capital - be indifferent

3.    Profitability Index

        This is a relative measure of projects profitability.  It is given by the following formula.
 

        Decision Rule

        If     PI > 1 - Accept the project
            PI < 1 - Reject the project
            PI = 1 - Be indifferent