Quartiles
Understanding quartiles and how they describe data distribution
What are quartiles?
Quartiles are values that divide an ordered dataset into four equal parts. Each part represents 25% of the data. Quartiles are commonly used to analyze data distribution and spread.
The three quartiles
There are three main quartiles used in statistics:
Q1 (First quartile): 25% of the data falls below this value
Q2 (Second quartile): The median of the dataset
Q3 (Third quartile): 75% of the data falls below this value
How to calculate quartiles
To calculate quartiles, first sort the data in ascending order. Then find the median (Q2), followed by the medians of the lower and upper halves of the dataset.
Example
Dataset: 4, 7, 10, 15, 18
Q1 = 7
Q2 (Median) = 10
Q3 = 15
Why are quartiles useful?
Quartiles help summarize large datasets, identify outliers, and visualize data using box plots. They are widely used in statistics, finance, and data analysis.