Comparative Analysis

My company is currently experiencing a quality problem that we’ve been spinning our wheels on.  There’s a large number of potential causes, along with a handful of knowledge we have learned that fits some but not others.  My thinking is that this is an excellent case to use comparative analysis.  The problem is that it’s been at least 3 years since I’ve done one and I’m a bit rusty.
 
Does anyone know where I can see a few case studies or other information to help me brush up?