Spread With STDEV and VAR

Two datasets can share the same average yet behave completely differently. One might cluster tightly around the mean; the other might swing wildly.

To capture that, you measure spread, also called dispersion. The two core tools are variance (VAR) and standard deviation (STDEV). Both answer the question: how far do the values typically stray from the average?

Variance is the average of the squared distances from the mean. Squaring does two things: it removes negative signs and it punishes big deviations more than small ones.

The downside is that variance is in squared units. If your data is in dollars, the variance is in dollars-squared, which is hard to interpret directly.