Home / Statistical Tools / Analysis Tools / Box Plot
Box Plot¶
Visualize the distribution of your data at a glance: see the median, spread, quartiles, and outliers in a single chart.
What is a Box Plot?¶
A box plot (also called a box-and-whisker diagram) summarizes a dataset using five key values:
- Median: the middle value, shown as a line inside the box
- Lower quartile (Q1): the 25th percentile, the bottom edge of the box
- Upper quartile (Q3): the 75th percentile, the top edge of the box
- Whiskers: lines extending from the box to show the range of typical values
- Outliers: individual points plotted beyond the whiskers
The box itself represents the interquartile range (IQR), the middle 50% of your data. This makes it easy to see at a glance where most values fall and whether any values are unusually high or low.
When to Use a Box Plot¶
- When you want to see the shape and spread of a distribution quickly
- When you need to compare distributions across multiple groups or columns side by side
- When you want to identify outliers or suspected outliers in your data
- When you need a compact summary of many data points without showing every individual value
Example Output¶
A typical box plot shows one or more boxes, each representing a column of data. The box spans from Q1 to Q3, the median line divides the box, whiskers extend to the most extreme non-outlier values, and any outliers appear as individual points beyond the whiskers.
What the sheet records about your settings¶
The User input box in the top left of the worksheet does not only echo the columns you picked. Under a Settings heading it also states the options that produced the chart below it, so a sheet opened a year later says what it was built from rather than leaving you to guess which boxes were ticked.
This matters most where the choice leaves no other trace. Two Pareto charts drawn from the same data, one grouping the small categories into an "Others" bar and one dropping them, look like two different data sets unless the sheet says which was done.
Two rules decide what appears:
- Every selector and checkbox is printed on every run, whether or not you changed it from the default. A reader who sees nothing cannot tell a default from a setting the product does not report, so the box states all of them.
- A value you had to type is printed only when you typed it, and so is a setting that only means something once another box is ticked. Its absence is the answer.
The worksheet is protected¶
Under the last block in column A, in small italic text, the sheet carries one note:
This worksheet is protected to prevent accidental changes. To unprotect it, select the Review tab and then Unprotect Sheet.
Every analysis worksheet Quantum XL writes is protected, and every one carries this note. The wording is the same on all of them. Protection is there so that a click or a stray keystroke cannot overwrite a number the chart is drawn from, or move a chart off its anchor.
Three things are still allowed while the sheet is protected: formatting cells, formatting columns, and formatting rows. So you can widen a column, change a number format, or restyle a heading without unprotecting anything. Editing a value, editing a chart, and everything else are blocked.
For those, unprotect the sheet from Excel's Review tab, exactly as the note says. The protection carries no password, so Unprotect Sheet takes it straight off without asking for one.
Under Settings, this tool records eight rows, because none of these choices can be read back off the chart: a marker series is simply there or not.
| Row | What it reads |
|---|---|
| Box height | Interquartile Range, or the percentile pair you chose, reading like 10th to 90th percentile |
| Whiskers | Minimum and maximum data point, or Lowest and highest datum within 1.5 x IQR of the quartiles |
| Dataset minimum, Dataset maximum, Mean, Outliers, Suspected outliers, Shared Y axis | each On or Off |
Learn More¶
- How-To: Step-by-step tutorials for different scenarios
- Preparing Your Data: Data types, layouts, and the behavior matrix
- Options: All chart settings and customization options