Question

Which values are outliers?

6.1, 3.9, 6.4, 10.6, 4.4, 4.5, 1.6, 11.2, 0.8, 3.9, 6.5

Select Outlier or Not Outlier for each data point.

Data Outlier Not Outlier
0.8
1.6
10.6
11.2

Answer 1

How to compute outliers:

1) Data in chronological order:
0.8 ; 1.6 ; 3.9 ; 3.9 ; 4.4 ; 4.5 ; 6.1 ; 6.4 ; 6.5 ; 10.6 ; 11.2

2) Get median: There are 11 numbers, the 6th number is the median.
median: 4.5

3) Get Q1 and Q3.
Q1: 3.9 ; Q3 = 6.45

4) Find IQR. IQR = Q3 - Q1
IQR = 6.45 - 3.9
IQR = 2.55

5) Find inner fence and outer fence:
Multiply IQR by 1.5 → 2.55 x 1.5 = 3.825
Add result to Q3: 6.45 + 3.825 = 10.275 outer fence
Deduct result from Q1: 3.9 - 3.825 = 0.075 inner fence

Outlier are outside the 0.075 - 10.275 range

Data Outlier Not Outlier
0.8 x
1.6 x
10.6 x
11.2 x