Definition
Quartile
A quartile is one of three cut points that divide ordered data into four parts.
View exact chart data
| Position | Quartile |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 2 |
| 6 | 2 |
| 7 | 2 |
| 8 | 2 |
| 9 | 3 |
| 10 | 3 |
| 11 | 3 |
| 12 | 3 |
| 13 | 4 |
| 14 | 4 |
| 15 | 4 |
| 16 | 4 |
What it means
Put the values in order, then imagine three gates across the list. Q1 is near one quarter of the way through, Q2 is the median halfway point, and Q3 is near three quarters. Rules for calculating Q1 and Q3 can differ, so use the method named in the task.
Remember it
Three cuts make four ordered quarters: Q1, the median, and Q3.
Example
Using the median-of-each-half method, order 2, 4, 5, 7, 9, 10, 12, 15. The median Q2 is 8, Q1 is 4.5, and Q3 is 11. Those three values mark the four ordered parts.
Watch for
A quartile is based on position in ordered data, not one quarter of the largest value.
Common mix-up
Q1, Q2, and Q3 are the three cut points; those three cuts create four parts.
Exact meaning
The lower quartile Q1, median Q2, and upper quartile Q3 are position-based cut points in ordered data. Together, these three quartile values divide the distribution into four parts.