The empirical rule describes how points are clustered in a normally-distributed data set. It states that 95% of data fall within two standard deviations of the mean.

According to the empirical rule, that's 99.7% of the data. ... Joint Probability: Definition, Formula, and Example. Sight Letter of Credit: Definition, How It Works, and Example.

Still, this means there’s just one example of Summers’ rule holding over nearly 75 years of economic data. That’s not exactly ironclad empirical evidence. Featured Fact-check ...