Quartiles, IQR & Percentiles
Section: Statistics & ProbabilityBank code: STA-IQRGRE frequency: MediumPro
1. Core Idea
Quartiles and percentiles describe position within sorted data, not the values themselves.
- Percentile: the pth percentile is the value below which p% of the data falls.
- Quartiles: the three values that split sorted data into four equal-sized parts.
The mental model: line everyone up shortest to tallest, then ask "where in the line does this person stand?"
The rest of this note is part of Pro
Must-know rules, three worked examples, the GRE traps, speed tricks and a self-check — plus every one of the 75 concept notes and all 8,390 questions.
Reading free? 25 notes are free, including every exam-strategy note.