## What Is the Mode?

The mode is the number that appears most frequently in a data set. A set of numbers may have one mode, more than one mode, or no mode at all. Other popular measures of central tendency include the mean, or the average (mean) of a set, and the median, the middle value in a set.

The mode can be the same value as the mean and/or median, but this is usually not the case.

## Understanding the Mode

In statistics, data are distributed in various ways. The most often cited distribution is the classic normal (bell-curve) distribution. In this, and some other distributions, the mean (average) value falls at the mid-point, which is also the peak frequency of observed values. For such a distribution, this value is also the modeāthe most frequently occurring value in the data.

### Key Takeaways

- In statistics, the mode is the most commonly observed value in a set of data.
- For the normal distribution, the mode is also the same value as the mean and median.
- In many cases, the modal value will differ from the average value in the data.

## Examples of the Mode

For example, in the following list of numbers, 16 is the mode since it appears more times in the set than any other number:

- 3, 3, 6, 9,
**16, 16, 16**, 27, 27, 37, 48

A set of numbers can have more than one mode (this is known as *bimodal *if there are two modes) if there are multiple numbers that occur with equal frequency, and more times than the others in the set.

**3, 3, 3**, 9,**16, 16, 16**, 27, 37, 48

In the above example, both the number 3 and the number 16 are modes as they each occur three times and no other number occurs more often.

If no number in a set of numbers occurs more than once, that set has no mode:

- 3, 6, 9, 16, 27, 37, 48

A set of numbers with two modes is **bimodal**, a set of numbers with three modes is **trimodal**, and a set of numbers with four or more nodes is **multimodal**.

## Advantages and Disadvantages of the Mode

### Advantages:

- The mode is easy to understand and calculate.
- The mode is not affected by extreme values.
- The mode is easy to identify in a data set and in a discrete frequency distribution.
- The mode is useful for qualitative data.
- The mode can be computed in an open-ended frequency table.
- The mode can be located graphically.

### Disadvantages:

- The mode is not defined when there are no repeats in a data set.
- The mode is not based on all values.
- The mode is unstable when the data consist of a small number of values.
- Sometimes data have one mode, more than one mode, or no mode at all.

### Fast Fact

When scientists or statisticians talk about the modal observation, they are referring to the most common observation.