The coefficient of variation (CV) is a statistical measure that expresses the standard deviation of a dataset as a percentage of its mean, providing a relative measure of dispersion that allows for comparison across different datasets with varying units or scales. It is calculated by dividing the standard deviation by the mean and then multiplying by 100. The empirical rule, also known as the 68-95-99.7 rule, applies to data that follows a normal distribution and states that approximately 68% of data falls within one standard deviation of the mean, 95% within two standard deviations, and 99.7% within three standard deviations. This rule helps to quickly assess the distribution of data and the likelihood of data points falling within certain ranges. Together, these concepts aid in understanding data variability and assessing how well data fits a normal distribution.