There are three different types of mode in statistics. They are:
- Unimodal distribution – A single unique mode.
- Bimodal distribution – The data has two modal values.
- Multimodal distribution – It has more than two values of mode.
We now define each of them and give one example of each type of distribution.
If we are given a set of data where we can define a single unique value for mode then the distribution is said to be unimodal. Recall that the mode is the value that occurs with the highest frequency.
Being unimodal means that there is a single value that occurs the greatest number of times. For example, consider the set of data given as:
1, 1, 2, 2, 2, 4, 6, 11, 17, 18.
Here, the data value 2 occurs with the highest frequency (three times) and therefore we have that,
Mode = 2.
In a bimodal distribution, we have two different values for the mode. This happens when two values occur in the data set the same number of times.
Since both the values occur with the highest frequency we declare both values to be the mode and the distribution is said to be bimodal. For example, consider the set of data values:
1, 2, 2, 2, 7, 7, 7, 1, 12, 18, 22, 36.
Here, the data values 2 and 7 occur with the greatest frequency.
Since both values occur an equal number of times we have two values for mode in this data set.
Mode = 2 and 7.
As the name suggests, here we have three or more values that occur with the highest frequency. For example, consider the set of data values:
13, 13, 15, 16, 16, 18, 18, 19, 23.
Here the data values 13, 16, and 18 all occur with the highest frequency (two times each) and so all three of these values are modal values.