3. Averages, Spread, and Uncertainty

Science often summarizes repeated measurements. The mean is the arithmetic average: add the values and divide by how many values there are. The median is the middle value after sorting. The range is the largest value minus the smallest.

The mean is useful when data is fairly balanced. The median is often better when there is an outlier, a value far from the rest. For example, in 4, 5, 5, 6, 100, the mean is pulled upward by 100. The median, 5, better represents a typical value.

Variation matters. Two groups can have the same mean but different spread. If one group has values tightly clustered and another has values scattered widely, the groups are not equally consistent.

The GED® may also ask about uncertainty. Repeated measurements, larger samples, and consistent patterns increase confidence. A tiny sample or highly variable data calls for caution.