- An observation which differs from an overall pattern on a sample dataset is called an outlier.
- The IQR method divides a data set into quartiles to measure variability.
- The information is arranged in ascending order and divided into four equal parts.(Q1, Q2, Q3, Q4)
- A dataset has 2n / 2n+1 data points, then (n > 2)
- Q1 : median of the dataset.
- Q2 : median of n smallest data points.
- Q3 : median of n highest data points.
- IQR is the range between the first and the third quartiles namely Q1 and Q3 (
IQR = Q3 - Q1
) - The outliers are data points which fall below
Q1 – 1.5*IQR
or aboveQ3 + 1.5*IQR
.