The first quartile (Q1), or the lower quartile, is the value that marks the 25th percentile of a dataset, meaning 25% of the data points fall below it. It is often used to understand the spread and distribution of data, especially when identifying outliers or describing variability.
For example, in a list of students’ test scores from lowest to highest, if the first quartile is 65, it means that 25% of the students scored below 65.
Synonyms:
Lower Quartile