4. Quantifying Downside Risk

See-saw with up arrow on one end and down arrow on the other end. Gear floating above see-saw. [NewTab]
Risk and reward have a strong positive correlation.

Standard deviation is an adequate measure of risk if the underlying distribution is normal; because the normal distribution is symmetric, the probability of observing a positive deviation from the mean is exactly equal to the probability of observing a negative deviation, equal to 0.5. In other words, half of the time we would observe negative deviations and half of the time positive deviations from the mean. If you want a measure of the negative deviations from the mean for a normal distribution, you can simply divide the standard deviation by 2.

However, the standard deviation is not an adequate measure of risk if the underlying distribution is not normal. In such cases, other measures of the shape of a distribution, such as skewness and kurtosis, will be informative in assessing risk.

License

Icon for the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License

Module 1: What Is Risk? Copyright © by Tsvetanka Karagyozova is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

Share This Book