May 2001

Vol. 3, No. 5

Quality Quiz from Dr. Cleary

You're right!

Will Ressque may have an opening with Mr. Drecters and his daughter if he learns this simple tool.

If two variables are related to each other in some way--as pH and time are in the example--a tool that can provide insight into the quality of the relationship is correlation analysis, or scattergrams. In cases where it can be determined that one factor has an effect on the other, this is known as regression analysis.

In regression analysis, the variable that is being predicted (pH levels, in this case) is called Y (dependent variable), and the one that causes the changes is known as the independent variable. (In this example, this would be time.) If Will were to use a scattergram to evaluate pH levels over time, it might look like this:


To access a more complete discussion of regression, including explanations of how to create scattergrams and when to use them, go to

Download Adobe Acrobat reader

This discussion is taken from Practical Tools for Continuous Improvement Vol. I, Statistical Tools, a component of the Total Quality Transformation training system. Call our toll-free number, 800-777-3020 for more information about these materials.


Copyright 2001 PQ Systems.

Please direct questions or problems regarding this web site to the Webmaster.