Outlier/Interquartile Range Calculator
Answer:
Interquartile range: 153
Outlier(s):
none
Potential outlier(s):
76, 252
See the outliers and potential outliers highlighted in the sorted data set here:
76, 252, 513, 525, 531, 535, 557, 565, 567, 582, 605, 629, 664, 681, 684, 684, 688, 693, 697, 698, 869
Solution:
The interquartile range, IQR, is the difference between Q3 and Q1. In this data set, Q3 is 686 and Q1 is 533. Subtract Q1, 533, from Q3, 686. $$ IQR = 686 - 533 = 153 $$ You can use the 5 number summary calculator to learn steps on how to manually find Q1 and Q3.
To find outliers and potential outliers in the data set, we first need to calculate the value of the inner fences and outer fences. The inner fences are defined by: $$ Q1 - (1.5 \cdot IQR) \text{ and } Q3 + (1.5 \cdot IQR) $$ For this data set: $$ 533 - (1.5 \cdot 153) \text{ and } 686 + (1.5 \cdot 153) $$ $$ \text{Inner fences: } 303.5 \text{ and } 915.5$$
The outer fences are defined by: $$ Q1 - (3 \cdot IQR) \text{ and } Q3 + (3 \cdot IQR) $$ For this data set: $$ 533 - (3 \cdot 153) \text{ and } 686 + (3 \cdot 153) $$ $$ \text{Outer fences: } 74 \text{ and } 1145 $$
The inner and outer fences are listed below. Potential outliers are any values in our data set that fall between the inner fences and outer fences, inclusive. Outliers are any values that fall outside of the outer fences.
| Outliers | Outer fence | Inner fence | Inner fence | Outer fence | Outliers |
| 74 | 303.5 | 915.5 | 1145 |
If there are any outliers in this data set, they will either be less than 74 or greater than 1145. Potential outliers will be between 74 and 303.5, inclusive or between 915.5 and 1145, inclusive.
In this data set, there are no outliers.
In this data set, the potential outlier(s) is/are:
76, 252