Real root causes

You hear a lot about "real root causes" in the Quality business. What's that mean and why do you care? 

Why you care is that if you fix a problem without fixing the root cause, it'll just happen again tomorrow. So the idea is not to fix it for a day, but to avoid that same problem — or any similar problems that are kind of like it — in the future. 

So what is a "real root cause"? That's a little harder. Let me start by giving examples of what it isn't: 

• A real root cause is not just a restatement of the problem. Let's say — this is a fictitious example! — that we get a batch of 5000 plastic housings from our supplier, and they all have a big ugly scratch across the front. Obviously no good. We call them to say we're rejecting the lot, and we ask for a root cause analysis why the housings were no good and how they got through the supplier's QA inspection. Suppose they answer, "The root cause for why the housings were no good is that they've got a big scratch on the front." Is that any help? Of course not. We already knew that. We wanted them to figure out how the housings got that way. In other words, they haven't found the real root cause.
   
  This sounds like a silly example, but in highly technical engineering problems it happens a lot. When the problem is very sophisticated, it is amazingly easy to think you've found a meaningful root cause when all you've done is to re-state the problem in totally different verbiage. Be warned. 
• A real root cause does not assign blame. I worked for a company once that hired a certain freight-forwarder, and this freight-forwarder mixed up a hugely important (and very expensive) order. We asked them for a root cause analysis. They replied that the root cause was a guy named Fred in their warehouse who was always making mistakes ... and as a Corrective Action they fired Fred! They sent us a copy of his pink slip as proof.
   
  But what good is that? Who's to say that the guy next to him — call him Max — won't make the very same mistake tomorrow? They never actually looked at how they process orders, to see if their system is confusing. 
• A real root cause has a clear causal connection to the problem. Take the plastic housing example, above. The real root cause will not turn out to be, "Oh that's because Mercury is retrograde in Taurus right now." It also won't be, "Gee, I dunno. These things just happen." 
• A real root cause is something you can fix. Out here in California we have wildfires from time to time. Sometimes they are caused by natural forces like lightning, and sometimes by human carelessness. The Zaca Fire, back in 2007, was started by sparks from a grinding machine. But clearly part of the reason these fires spread is that Earth has oxygen in its atmosphere. Right? No oxygen, no wildfire. But it doesn't help to call that a root cause unless we can seriously entertain the option of moving to Mars. 
• "Human error" is not a real root cause. This is a special case of the previous point. We'll never get rid of "human error" any more than we can live on a planet without oxygen. The whole point of a Quality System is that you start by assuming that human beings make mistakes, and so you build in safeguards to reduce the likelihood or the impact of those mistakes to a minimum. 

With those cautions as a background, investigate the causes of a failure. You'll probably end up with a chain like this: "A was caused by B, which was caused by C, which was caused by D ...." Did they lead you to a real root cause? Well, you can test them: 

• First, make sure that each step in the chain really does represent a causal link that makes sense. You should be able to re-word your whole causal chain as, "D, so as a result C, so as a result B, so as a result A." If it makes no sense that way, keep looking. 
• Second, make sure there's nothing personal in the causal chain. (More exactly, "Fred had a hangover" might be a legitimate cause but "Fred's an idiot" is not.) The assumption is always that everybody is trying his best to do a good job, so anybody could make the same mistakes Fred made. 
• Third, make sure there's something you can do about each step. Telling everybody to "be more careful next time" does nothing to solve the problem. 
• How far do you push it? As far as makes sense. Typically that means push it as far as you can go and still derive some meaningful countermeasures. That's your real root cause.