Chapter 9 RisT and return 9. 4 The variability of returns: the second lesson Frequency distributions and variability To get started, we can draw a frequency distribution for the common stock returns like the figure What we need to do is to actually measure the spread in eturns. We now want to know how far the actual return deviates from the average in a typical year. In other words. we need a measure of how volatile the future is. The variance and its square root, the standard deviation, are the most commonly used measures of volatility.Chapter 9 Risk and return 9.4 The variability of returns: the second lesson – Frequency distributions and variability To get started, we can draw a frequency distribution for the common stock returns like the figure. What we need to do is to actually measure the spread in returns. We now want to know how far the actual return deviates from the average in a typical year. In other words, we need a measure of how volatile the future is. The variance and its square root, the standard deviation, are the most commonly used measures of volatility