# 6.10.6 Weibull Probability Plot

## Summary

The probability plot shows a graph with observed cumulative percentage on X axis and expected cumulative percentage on Y axis. The Weibull probability plot is used to test whether or not a dataset follows Weibull distribution. And its X scale type and Y scale type are Log10 and Double Log Reciprocal respectively. If all the scatter points are close to the reference line, we can say that the dataset follows the Weibull distribution. ## What you will learn

• How to create a Weibull probability plot
• How to add the fill area between the percentiles lines

## Steps

You can refer to this graph in Learning Center. (Select Help: Learning Center menu or press F11 key , and then open Graph Sample: Statistical Graphs and search "weibull")

1. Download the data from here. Drag and drop the downloaded txt file into the active worksheet. Highlight column A and right-click to select Set As: Y from the context menu.
2. Keep this column highlighted, select Plot > Statistical : Probability Plot from the Origin main menu to open the plot_prob dialog. In this dialog, change Distribution to Weibull and then click the OK button to create a Weibull probability plot with column A. 3. Double-click on the Lower Percentiles line to open the Plot Details dialog. Go to the Line tab, set Color to Red, Transparency to 80%, then check Fill Area Under Curve check box and select Fill to next data plot - One Color in the below drop-down list. 4. Go to Pattern tab, set Fill Color to Red. And make sure the Follow line transparency is checked. 5. Go to the Line tab of Upper Percentiles line set Color to Red, Transparency to 80%. Click OK to apply the setting and close the dialog. 6. Click on the X axis on the graph, and in the popup mini toolbar, click the Axis Scale button to open the Axis Scale dialog to change the scale to be from 10 to 100, and set the Tick Increment to 20. 7. In the Axis Scale dialog, switch to Vertical axis, and change scale from 1 to 99.99. Click OK to apply the setting and close the dialog. The final graph should look like this: 