The empirical rule describes how points are clustered in a normally-distributed data set. It states that 95% of data fall ...

In statistics, the average amount a number varies from the average number in a series of numbers. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction requires permission.

Standard deviation describes how much variability—or fluctuation—exists within a data set. The standard error of the mean (SEM) indicates how accurately a data set represents the true population by ...

Learn what residual standard deviation is, how to calculate it in regression analysis, and why it's crucial for measuring predictability and goodness-of-fit in data modeling.

The Journal of Educational Research is a well-known and respected periodical journal that reaches an international audience of educators and others concerned with cutting-edge theories and proposals.

When you're trying to estimate the time between the beginning and the end of any project, the critical path follows the longest route. The standard deviation, on the other hand, uses the the most ...

In response to my article, Is the Stock Market Too Concentrated?, which relied upon standard-deviation calculations to assess investment risk, a reader wrote: “My problem [with your argument] is ...