Standard Deviations 4 / 5

Using Standard Deviation To Measure Risk

Co-Efficient of Variation

Standard deviation / expected value (mean)

Illustration 1

Alpha Co is considering investing in one of the following projects:

ProjectExpected value $000Standard deviation $000
A950600
B1,400580
C250300
D760740

Required

If Alpha Co wishes to select the project with the lowest risk factor (coefficient of variation) it will select project:

  • SOLUTION

    Coefficient of variation = Standard deviation / expected value (mean)

    A = 600 / 950 = 0.63
    B = 580 / 1,400 = 0.41
    C = 300 / 250 = 1.2
    D = 740 / 760 = 0.97

    Lowest risk factor (coefficient of variation) = project B

Illustration 2

Beta Co is considering investing in one of two mutually exclusive projects.

Information about the projects is shown below:

Project AProject B
Expected value of profit$165,000$199,000
Standard deviation$51,533$133,389

Required

If the management of Beta Co are risk averse, which project would they be most likely to invest in?

  • SOLUTION

    On the basis of EVs alone, project B is marginally preferable to project A, by $34,000. ($199,000-$165,000 = $34,000).

    However, if the management are risk averse, they would be more likely to choose project A because, although it has a smaller EV, the possible profits are subject to less variation.

    This is demonstrated through a smaller standard deviation.

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