XLSTAT: Contour Plots in Excel

 

Background

If you want to visualize (for example) the topography of a volcano, XLSTAT will allow you to do this with a contour plot.

 

Dataset for Example

The data are fictitious data representing the topography of a volcano on a 10 m by 10 m grid. The X and Y columns are therefore the coordinates of the grid, and the altitude column represents the altitude at each point of the grid.

 

Setting Up

• Open XLSTAT.

• Click on the Visualizing data menu and select the Contour Plot feature:

• The dialog box pops up.

In the General tab:

• Select column A in field X,

• Column B in field  Y,

• Column C in field  Z.

In the Options tab:

• Check Contour plot.

 

• Click on the OK button to launch the computations.

• The results are displayed on a new Excel sheet.

 

Interpreting the Results

The contour plot is displayed:

The contour plot shows the different altitude zones.

On the right side of the plot, a low area represents the beginning of the plain. The other areas surround the volcano up to its summit with an altitude which increases gradually, until reaching the center of the summit where the altitude drops suddenly. 
To see the shape of the volcano more clearly, you can display the plot as a 3D surface .

 
In this way we identify the same conclusions as made with the 2D contour plot with the plain on the right, and the different altitude zones up to the summit of the volcano.

Note:

In the example, the data is sufficient to have a good view of the volcano. 

When there is very little data or missing data at some points on the grid, XLSTAT allows you to perform an interpolation (bilinear or bicubic) of the points and thus make the graph more readable.