Re-Thinking CAPA

CAPA is an acronym for “Corrective Action / Preventive Action”. If you've been involved with the Quality profession for longer than 10 minutes, you've probably heard this term.

The short answer is because CAPA makes a general assumption that is often incorrect.

To explain this, let's quickly cover the definitions for these two terms. For sake of consistency, I'll use the definitions provided in ISO 9000:2015, “Quality management systems–Fundamentals and Vocabulary”.

3.21.1
Preventive Action
action to eliminate the cause of a potential nonconformity or other potential undesirable situation

Note 1 to entry: There can be more than one cause for a potential nonconformity.
Note 2 to entry: Preventive action is taken to prevent occurrence whereas corrective action is taken to prevent recurrence.

3.12.2
corrective action
action to eliminate the cause of a nonconformity (3.6.9) and to prevent recurrence

Note 1 to entry: There can be more than one cause for a nonconformity.
Note 2 to entry: Corrective action is taken to prevent recurrence whereas preventive action (3.12.1) is taken to prevent occurrence.
Note 3 to entry: This constitutes one of the common terms and core definitions for ISO management system standards given in Annex SL of the Consolidated ISO Supplement to the ISO/IEC Directives, Part 1. The original definition has been modified by adding Notes 1 and 2 to entry.

It is vitally important to note that each definition begins with “action to eliminate the cause”. This is the “general assumption” mentioned above.

The concept of “CAPA” is most popular among supporters of the “Zero Defects” motivational management approach. The term “Zero Defects” first appeared in the “Quality and Reliability Assurance Handbook – A Guide to Zero Defects” (4155.12H) published by the U.S. Department of Defense on November 1, 1965, which explained: “Zero Defects is a motivational approach to the elimination of defects attributable to human error”. And “Zero Defects is dedicated to preventing defects by detecting and removing the causes of their generation. This is an attempt to reverse the unquestioning acceptance of human error as a normal byproduct of personal effort”.

However, the “Zero Defects” concept didn’t gain widespread popularity until it was promoted by Philip B. Crosby in his book “Quality is Free” (1979). Crosby is credited with having developed the “Zero Defects” concept during the early ‘60s while working at the Martin Company as the quality control manager overseeing the Pershing missile program

However, there is a MAJOR flaw in the “Zero Defects” concept… as it establishes an unrealistic expectation that every problem has an assignable root cause that can be eliminated.

To suggest (or imply) that all defects are the result of an “assignable cause” is to dismiss all that we’ve learned from Walter A. Shewhart & W. Edwards Deming!

W. Edwards Deming repeatedly demonstrated that, no matter how vigilant the employees, every process contains inherent (i.e., natural) “Common Cause” variations resulting in defects. This was most popularly demonstrated through Deming’s “Red Bead Experiment”. In fact, point 10 of Deming's 14 points specifically rejects the “Zero Defects” concept, stating: “Eliminate slogans, exhortations, and targets for the work force asking for zero defects and new levels of productivity. Such exhortations only create adversarial relationships, as the bulk of the causes of low quality and low productivity belong to the system and thus lie beyond the power of the work force”.