Key Variance Analysis comes from the literature on Socio-Technical Systems

An excellent, but probably unpublished, explanation, called "A Socio-Technical Analysis (including a variance matrix and a social systems grid) for The Cotter-Cherns Scottish Sandwich Corp., Ltd.," comes from E. Lauck Parke, now Associate Dean of Undergraduate Education at the University of Vermont.

The Key Variance Analysis lists the steps in a (any) production process and, within each step, what can go wrong.  The following example uses this tool to analyze the ranking of XB Memos:

Start correcting memos Don't start soon enough
Initial Memo People don't initial memos
Comment on Memo Don't correct grammar and spelling errors
Write the same thing on everyone's memo
Don't offer suggestions
Don't write enough
Rank Memos Don't have sufficient means to rank
Bias
E-mail list of ranks to Control Forget to do it
E-mail is down
Mis type names
Put memos outside Sr. Mgr's office Area is locked
Can't find the right folder
Forget to do it