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Control chart axes

tim_reeves

Community Trekker

Joined:

Jun 10, 2016

Is there any way to change the y axis of a run chart (or any control chart) to logarithmic? For some data distributions, it would be helpful, but it doesn't appear to be possible.

2 REPLIES
Peter_Bartell

Joined:

Jun 5, 2014

It doesn't appear as though you can scale the y axis on a control or run chart as you suggest. What I did was use the Fit Y by X platform, placing the process factor on the y axis, and your 'Label' on the x axis. You may have to modify the x axis with Value Ordering? Then from the report hot spot, select Flexible -> Fit Each Value. This will connect all the points with a straight line between each point. Then modify the y axis scaling as one would normally to Log. If you've got control limits, you could manually add those as reference lines...cumbersome. But doable.

Here's what it looks like:

11806_pastedImage_0.png

Steven_Moore

Super User

Joined:

Jun 4, 2014

Control charts are very powerful WITHOUT transforming the data.  Transformations are virtually always useless for gaining knowledge about your process.  I suggest you Google Donald Wheeler's articles on the subject. 

Steve