Quintile
Quintile refers to one of the four cut points that divide ranked data into five equal 20% groups, used alongside quartiles and deciles to describe distributions of income or performance.
What it is
See it move
Ten students' exam scores, ranked ascending, are 42, 48, 55, 58, 61, 64, 67, 70, 75 and 88. The first quintile's position is (1 ÷ 5) × (10 + 1) = 2.2, landing between the 2nd ranked value, 48, and the 3rd, 55. Interpolating 0.2 of the way gives 48 + 0.2 × (55 − 48) = 49.4, meaning roughly 20% of students scored below this mark.
The formula
Variables
- Position of the kth quintile in the sorted data
- Quintile number (1 to 4)
- Number of values (observations)
Locates the ranked position of the kth quintile (k = 1 to 4); a fractional result means interpolating between the two nearest ranked values.
Check yourself
A retailer ranks 15 stores by monthly revenue from lowest to highest (in thousands of euros): 40, 42, 45, 47, 50, 52, 55, 58, 60, 63, 66, 70, 74, 79, 85. What is the 4th quintile (the 80th-percentile cut point)?