The empirical rule, or the three-sigma rule, is a statistical method that helps interpret the value of a standard deviation in normally distributed data. For example, the height of NBA players follows a bell-shaped distribution, with a mean of 190 cm and a standard deviation of 18 cm. The empirical rule predicts that sixty-eight percent of all values fall within one standard deviation, ninety-five percent fall within two standard deviations, and ninety-nine point seven percent fall within three standard deviations of the mean. The empirical rule is widely used in statistics to help estimate the proportion and range of data values using the standard deviation. It also helps determine the upper and lower control limits for statistical quality control and risk analysis. In economics, the empirical rule is relevant in predicting stock prices and forex rates. The major drawback of this rule is that it only applies to datasets with normal distribution.