Data Handling and Statistics
Quartiles
Quartiles divide a sorted dataset into four equal parts. The median (Q2) is the middle value. The lower quartile (Q1) is the median of the lower half, and the upper quartile (Q3) is the median of the upper half.
Worked Example
For the sorted dataset 2, 5, 7, 9, 12, 15, 18 (7 values):
- Median (Q2) = 4th value = 9
- Q1 = median of lower half (2, 5, 7) = 5
- Q3 = median of upper half (12, 15, 18) = 15
Practice: Quartiles
Find the median, Q1, or Q3 of a sorted dataset.