Whittaker's patented process of measuring the appearance of soil to schedule cleaning frequencies and determine the effectiveness of cleaning techniques is described in the PDF document below.
When Should Carpet Be Cleaned? - White Paper PDF September 2009
Science of Cleaning article by Dick Whittaker C&MM Magazine, October 2007
This process was recognized at ACUHO-I's 21st Century Project Product Showcase and was presented at CIRI's 2008 Cleaning Science Conference and Symposium.