XLSTAT: Scatter Plot in Excel

Dataset for Example

The data correspond to a small group of patients that have been on a specific diet. Their doctor has recorded their Weight before the treatment (kg), how much weight they've lost (kg), if they are satisfied or not with the diet effect, as well as their Age.

Our goal is here to visualize the results while keeping as much information as possible.

 

Setting Up

• Open XLSTAT.

• Click on the Visualizing data menu and select the Scatter Plots feature:

•  Once you have clicked on the button, the Scatter Plot dialog box appears.

In the General tab:

• Select the data on the Excel sheet as follows:

  X: Weight;

  Y: Weight loss;

  Z: Age;

  Groups: Satisfied.

In the Options tab:

• Activate the Frequencies and Only if >1 as we want to know if two or more points are superimposed if there is such a case.

• Activate the Legend option to be able to identify points belonging to each of the two categories of the Groups column.

Note: The Confidence Ellipses option can only be activated if the Z data option is deactivated in the General tab. 

In the Colors tab:

• First, enter the number of groups (here, we have yes/no so in total 2 groups).

• Then click on each group field below to choose its color. Note: If you want to leave the default XLSTAT colors, do not check the group number option.

• Click on the OK button to launch the computations.

• The results are displayed on a new Excel sheet.

 

Interpreting the Results

The following chart is displayed on the sheet:

Bubble size is proportional to the Z variable (age in our case) and is thus a way to represent the third dimension of our two-dimensional plot. Here, for example, we see that satisfied people are relatively old.

Note 1: For one of the observations a label has been added. This tells us that two observations are superimposed.

Note 2: The observations labels haven't been used on the chart because the "Observations labels" option was not checked.