Outlier Definition

In a data set, the value that stands far from the average values in that set is called an outlier.

For example, you have the following set of numbers

3, 4, 5, 19, 78, 20, 33, 12, 18, 23, 25

In this collection of numbers, 78 is an outlier because it is far apart from the other values of the set. Simply, we can say that a value from a set that stands outside is called an outlier.


You can read about the Data here.

How to identify an outlier from a number line?

As we know, a set of values can be shown on a number line easily. So, we can also find the outlier of the set (if it occurs) from it. Here are the steps to follow in this regard.


Read about Number Line here.

  • Draw a number line
  • Represents all the numbers given in the set
  • Find the point showing a number far from the other values of the set
  • That value will be an outlier of that set

What is the opposite of an outlier?

Like other terms in Mathematics, outlier also has an opposite term that is called standard. It contains all those values that are not far from other values but close to each other.


What is an outlier in simple words?

It is a quantity that lies apart from other quantities of a data set.

How do you determine an outlier?

An outlier can be found by showing all numbers on a number line. The value that is shown far apart from others will be an outlier.

Is the outlier affect the standard deviation?

Yes, an outlier can affect the standard deviation from the average of the data set.

What is the significance of an outlier?

An outlier is useful in solving different mathematical and statistical problems.