Quartile is another term referred to in percentile measure. The total of 100% is partitioned in three places, Q1, Q2, and Q3.
- Lower Quartile is the 25th percentile. (0.25)
- Median Quartile is the 50th percentile. (0.50)
- Upper Quartile is the 75th percentile. (0.75)
Example:
| Test Scores | Frequency | Cumulative Frequency |
| 76-80 |
3 |
3 |
| 81-85 |
7 |
10 |
| 86-90 |
6 |
16 |
| 91-95 |
4 |
20 |
The total frequency is 20.
The quartile information for this data is:
Lower Quartile 0.25 · 20 = 5 The lower quartile falls in the interval 81 – 85.
Median Quartile 0.50 · 20 = 10 The median quartile falls in the interval 81 – 85.
Upper Quartile 0.75 · 20 = 15 The upper quartile falls in the interval 86 – 90.
Median Quartile 0.50 · 20 = 10 The median quartile falls in the interval 81 – 85.
Upper Quartile 0.75 · 20 = 15 The upper quartile falls in the interval 86 – 90.
