Question

What is a bimodal distribution?

Answer 1

Hint: Data distributions in statistics can have one peak, or they can have several peaks. The type of distribution you might be familiar with seeing is the normal distribution, or bell curve, which has one peak. The bimodal distribution has $$2$$ peaks.

Complete step by step solution:
The “bi” in bimodal distribution refers to “$$2$$” and modal refers to the peaks. The two peaks in a bimodal distribution also represent two local maximums; these are points where the data points stop increasing and start decreasing.
For example, the distribution of heights in a sample of adults might have two peaks, one for women and one for men.
Another example is exam scores which tend to be normally distributed with a single peak. However, grades sometimes fall into a bimodal distribution with a lot of students getting A grades and a lot getting F grades. This can tell you that you are looking at two different groups of students. It could be that one group is underprepared for the class (perhaps because of a lack of previous classes). The other group may have over prepared.
Bimodal distribution showing two normal distribution curves combined, to show peaks in following diagram:

Bimodal distributions are a commonly used example of how summary statistics such as the mean, median, and standard deviation can be deceptive when used on an arbitrary distribution. Application of bimodal distribution to the detection of changes in uranium concentration in drinking water is notable.

Note:
Sometimes, what appears to be a bimodal distribution is actually two unimodal (one-peaked) distributions graphed on the same axis. Multimodal distributions have more than two peaks. Although bimodal (or multimodal) distributions can be revealing of systematic biases or issues, they often occur naturally as well. These naturally bimodal distributed variables include the colour of galaxies, the size of worker weaver ants, the age of incidence of Hodgkin’s lymphoma, traffic analysis, water demand etc.