Mean, Median, Mode, and Range: Basic Statistics Explained

These four measures — mean, median, mode, and range — are the foundation of descriptive statistics. They summarize a dataset into a handful of numbers, but they each answer a different question about the data. Knowing which one to use (and when the "average" misleads) is a genuinely useful skill.

Mean, median, and mode

The mean (arithmetic average) sums all values and divides by count. The median is the middle value when data is sorted. The mode is the most frequently occurring value. For the dataset {2, 3, 3, 7, 100}: mean = 23 (pulled up by the outlier 100), median = 3 (more representative), mode = 3 (most common).

When to use each measure

Use the mean for symmetric, outlier-free data. Use the median when outliers or skew are present (income data, where a few very high earners distort the mean). Use the mode for categorical data (most popular product size). The statistics calculator shows all three simultaneously.

Range and why it matters

Range = maximum − minimum. It tells you the spread of the data but is sensitive to outliers. For a more robust spread measure, use standard deviation, which accounts for every data point. The statistics calculator shows both.