First quartile: what it means and how to read it
In the report: q1 — The first quartile: 25% of the values are below it; computed as in SPSS, so it can differ from the Sheets QUARTILE and PERCENTILE functions.
How to read it
The lower edge of the middle half of the answers. With the median and q3 it describes skewed data better than the mean and std.
In plain words
A teacher had 40 marks and wanted to know which mark cuts off the lowest quarter of her class. She asked for q1 and got 55. So a quarter of the students got less than 55. Now she can say that a student with 52 is in the lowest quarter, and a student with 60 is not. Together with the middle mark and q3, it describes lopsided marks better than the average does. The add-on counts it the way the program SPSS does, so the answer can differ a little from the QUARTILE and PERCENTILE functions in Google Sheets.
How it is computed
The value at the position (n + 1) · 25 / 100 of the sorted values, interpolated between neighbours (SPSS EXAMINE, HAVERAGE); before the first value — the minimum, past the last — the maximum.Example
The cell with q1 is selected in each report; point at a label to see its note.
- — the sample data (50 rows) the examples use
- — Quartiles and percentiles as in SPSS
=STATS_DESCRIPTIVE(Data!A1:T51, "q1,median,q3,iqr,percentile.12.5", "x,x1")
Where you see it
STATS_DESCRIPTIVE— Column-wise descriptive statistics with flexible metric selection and optional column filtering.
Related values
- Third quartile — The third quartile: 75% of the values are below it; computed as in SPSS, so it can differ from the Sheets QUARTILE and PERCENTILE functions.
- 10th percentile — The 10th percentile: 10% of the values are below it; computed as in SPSS, so it can differ from the Sheets QUARTILE and PERCENTILE functions.
- 90th percentile — The 90th percentile: 90% of the values are below it; computed as in SPSS, so it can differ from the Sheets QUARTILE and PERCENTILE functions.
- Interquartile range — q3 − q1.
- Percentile — The q-th percentile, q from 0 to 100, fractions allowed (percentile.12.5); computed as in SPSS, like the quartiles. percentile.0.95 is the 0.95th percentile, not the 95th. Without q or with q outside 0…100 the cell is empty and the error is listed under the table.
Get it in your sheet
One formula in a cell gives the whole report, First quartile included. ALS Stats is a free add-on for Google Sheets™.
Install ALS Stats from Google Workspace Marketplace (opens in a new tab)