Which Data Is an Outlier?

An outlier is defined as being any point of data that lies over 1.5 IQRs below the first quartile (Q₁) or above the third quartile (Q₃)in a data set.

How do you find outliers in data?

Determining Outliers

Multiplying the interquartile range (IQR) by 1.5 will give us a way to determine whether a certain value is an outlier. If we subtract 1.5 x IQR from the first quartile, any data values that are less than this number are considered outliers.

What is an outlier in a data set?

An outlier is an observation that lies an abnormal distance from other values in a random sample from a population. In a sense, this definition leaves it up to the analyst (or a consensus process) to decide what will be considered abnormal. ... These points are often referred to as outliers.