Identifying outliers
An outlier is a data point that varies significantly from the body of the data. An outlier will be a value that is either significantly larger or smaller than other observations. In this lesson, we will visually identify outliers present in a set of data. Outliers are important to identify as they point to unusual bits of data that may require further investigation. For example, if you had data on the temperature in a volcanic lake and we had a high outlier, it is worth investigating if the sensor is faulty or we need to prepare a nearby town for evacuation.
Consider the dot plot below. We would call $9$9 an outlier as it is well above the body of the data.
Practice questions
Question 1
Identify the outlier(s) in the data set $\left\{73,77,81,86,131\right\}${73,77,81,86,131}.
Question 2
The dot plot shows the temperature ($^\circ C$°C) in a town over a several week period. Identify the temperature that is an outlier.
