# Notched box plots tutorial in Excel

This tutorial shows how to draw and interpret notched box plots in **Excel** using the XLSTAT software.

## Dataset for drawing a notched box plot

A description of the dataset as well as a guide to interpret classic box plots is available in the XLSTAT classic box plots tutorial.

In this tutorial, we add the **notched** option to the Box plots that are generated in the box plots tutorial. Notches allow to visualize a form of confidence intervals around the medians. When sample sizes are similar, notches allow to say roughly if medians are different or not.

## Setting up the dialog box for the notched box plots

Once XLSTAT is open, select the **XLSTAT / Visualizing data / Univariate plots** command, or click on the corresponding button of the **Visualizing data** toolbar (see below).

Once you have clicked on the button, the **Descriptive Statistics** dialog box appears.

Follow all the steps that are described in the classical box plots tutorial, but make sure that the **notched** option is activated in the **Charts (1) / Options** tab.

## Interpreting notched box plots

The results are displayed on the new sheet named "Desc".

After a table summarizing descriptive statistics, the **notched box plots** appear.

One box plot per species is displayed.

The red crosses correspond to the **means**. The central horizontal bars are the **medians**. **Notches** limits represent confidence intervals around medians. As notched areas do not overlap across box plots, we may expect that the three medians are different from one another. Please refer to Mood’s test to test for the null hypothesis of median equality. Box (vertical) thickness represents the **InterQuartile Range** (IQR) and allows to visualize the dispersion of 50% of the central data points around the median.

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