As an example of an unsuspected influence to a process, let’s looking at a metal machining process.  Here we have a drill bit that bathed in coolant that is used in manifold production.  The coolant is collected in a trough on the floor and reused until it goes bad.   The company is having a big problem – the coolant is going rancid and losing its ability to cool so quickly that they can’t replace the coolant fast enough.  The drill bit gets too hot and breaks.  They have to fly a new bit down from Michigan and the plant is located near Brownsville, TX.  It’s a $1million/day operation so down time is really costly.  Let’s compare to pictures of the process area.  How does the floor look different from one picture to the next?