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IAI Actuarial Core Principles · Economic Modelling · Measures of investment risk

Over 5 years a portfolio's annual active returns relative to its benchmark were: +2%, -1%, +3%, 0% and +1%. Using the sample standard deviation (divisor n-1), what is the tracking error, to two decimal places?

The tracking error is 1.58%. The mean active return is 1%, the sum of squared deviations is 10, the sample variance is 10/4 = 2.5, and its square root is about 1.58%. Dividing by n instead would wrongly give 1.41%.

  1. A1.00%
  2. B1.58%Correct
  3. C1.41%
  4. D1.79%
  5. 2.00%

Explanation

Mean = (2-1+3+0+1)/5 = 1. Deviations: 1, -2, 2, -1, 0; squares: 1+4+4+1+0 = 10. Sample variance = 10/4 = 2.5, so the standard deviation = 1.58%. Using divisor n gives variance 2, i.e. 1.41%, which is the wrong divisor.

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