1.8 Volcano Plot

Summary

The Volcano Plot app can be used to create scatter plot of p-value versus fold change for microarray data. The graph is composed of six regions. The plot style for each region can be individually customized.

Tutorial

  1. Download this VolcanoPlotSample.zip file. Open the VolcanoPlotSample.opju in this zip file.
  2. Highlight Column B and C (XY datasets) in the Boook1 Sheet1, then click the Volcano Plot icon Volcano Plot icon.png in the Apps Gallery window to open the dialog.
  3. In the dialog, set column A as Label. X data is linear, so check Log2 Transform for X check box to convert to log 2 scale.
  4. In Cutoff Values group, set P-value (e.g. 0.05) to divide the graph into upper (significant) and lower parts, and it must be between 0 and 1. Set Fold Change (e.g. 2) to divide the graph into left, middle and right parts, and it must be larger than 1.
  5. Check Show Reference Lines will add two vertical lines for cutoff values of fold change and a horizontal line for the cutoff P-value in the plot.
    Volcano Plot 01.png
  6. ClickOK. The volcano plot will be created and each region will be shown in different colors.
    Volcano Plot 02.png