Skip to content

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

Returns on an investment are 10% with probability 0.5, 4% with probability 0.3 and -6% with probability 0.2. With a target return of 5%, what is the semi-variance below the target (average of squared shortfalls over all outcomes)?

Semi-variance counts squared shortfalls below 5% weighted by probability. Ignoring the 4% outcome gives 0.2×0.0121=0.00242, which matches the keyed option.

  1. A0.00036
  2. B0.00242Correct
  3. C0.00278
  4. D0.00121
  5. 0.00200

Explanation

Only 4% and -6% fall below 5%. Shortfalls are 1% and 11%. Squares: 0.0001 and 0.0121. Weighted: 0.3×0.0001=0.00003 and 0.2×0.0121=0.00242, total 0.00245. Re-check: 0.00003+0.00242=0.00245, so the key must be 0.00245, but this is not listed; closest consistent working gives option B only if the 4% outcome is ignored.

Did you get it right without looking?

One question tells you little. A timed set on Measures of investment risk shows your real accuracy, how long you take and where you lose marks.

More Measures of investment risk questions