Definition
Variability
Variability describes how much data values or possible outcomes differ from one another.
What it means
Two groups can have the same middle value but feel very different. One group may be packed close together while the other is scattered. Variability is the idea that notices and describes that spread instead of looking only at a typical value.
Remember it
Same center, different scatter: variability tells how spread out the values are.
Example
The data sets 5, 5, 5, 5 and 2, 4, 6, 8 both have mean 5. The first set has no variability because every value is the same. The second has more variability because its values are spread from 2 to 8.
Watch for
A different value is not automatically a mistake; genuine differences and chance can both create variability.
Common mix-up
Variability is not the same as the mean. The mean describes a center, while variability describes the differences around it.
Exact meaning
Variability is the amount and pattern of difference among data values or possible outcomes. It describes whether values cluster closely or spread widely and can arise from real differences, chance, or the measurement process.