Question

In the group of scores 2, 81, 82, 82, and 84, the outlier is

Answer 1

A commonly used rule says that a data point is an outlier if it is more than 1.5 * IQR above

the third quartile or below the first quartile. Said differently, low outlier are below Q₁ - 1.5 * IQR and high outliers are above Q_{3 +} 1.5 * IQR

summary(x)
Min. 1st Qu. Median Mean 3rd Qu. Max.
2.0 81.0 82.0 66.2 82.0 84.0

IQR= Q1 - Q₃ = 82-81=1   

Below the Q₁ - 1.5 * IQR = 81- (1.5 * 1) = 79.5 (round the value 80)

Above the Q₃ + 1.5 * IQR = 82 +(1.5*1) =  83.5 (round the value 84)

so the outlier is 2.

if the value not round then the 2 and 84