Statistical variability vs. probabilistic uncertainty

The concepts of variability and uncertainty came from experience and coexist with different connotations. First, the article reviews the statistical methods for variability assessments of probability distributions. Next, it sums up the entropy concept of uncertainty of systems of events in probability theory. The two concepts are brought closer together on the basis of common experience of predictability. The article also considers the concept of average number of equally probable events based on entropy. Then, it introduces the concept of equivalent number of outcomes based on variability of probability distributions. Finally, the link between variability and uncertainty is illustrated with examples.