What Are Mean, Median, and Mode?
Mean, median, and mode are the three most common measures of central tendency — they each describe the "center" of a dataset in a different way.
- Mean (average) — the sum of all values divided by the count. Sensitive to outliers.
- Median — the middle value when sorted. Resistant to outliers.
- Mode — the most frequently occurring value. Can have zero, one, or multiple modes.
How to Calculate Each One
Mean
Mean = Σx / n
Add all values, then divide by the count. Example: (3 + 7 + 7 + 12 + 15) / 5 = 8.8
Median
Sort the values. If odd count, take the middle value. If even count, average the two middle values. Example: sorted [3, 7, 7, 12, 15] → median = 7.
Mode
Count how often each value appears. The value with the highest frequency is the mode. Example: [3, 7, 7, 12, 15] → mode = 7 (appears twice).
Mean vs Median: Which One to Use?
The mean works best when your data is roughly symmetric and has no extreme outliers. The median is better when data is skewed — for example, income data where a few very high earners pull the mean upward.
A good rule of thumb: if the mean and median are far apart, your data is skewed, and the median is likely more representative of the "typical" value.
Frequently Asked Questions
What if my dataset has no mode?
If every value appears the same number of times, there is no mode. This is common in datasets with all unique values.
Can a dataset have multiple modes?
Yes. A dataset with two modes is called bimodal, three modes is trimodal, and more than three is multimodal.
How do I calculate mean, median, mode in Excel?
Use =AVERAGE() for mean, =MEDIAN() for median, and =MODE() or =MODE.MULT() for mode in Excel or Google Sheets.
When should I use mean vs median?
Use mean for symmetric data without outliers. Use median for skewed data or data with outliers (like income, house prices). If mean and median differ a lot, the data is probably skewed.