(EN) Strengths and Weaknesses of the Eight Disciplines Problem Solving (8D)

In this (by now rather long) series of blog posts on the Eight Disciplines Problem Solving (8D) I have explained the nine (!) steps of the 8D in detail. In this last blog post of this series, I will now look at the strengths and weaknesses of the Eight Disciplines Problem Solving, especially in comparison to the Toyota Practical Problem Solving (PPS). Both aim to solve problems, but do so slightly differently. Let me give you my thoughts…

A Quick Recap

Here are (again) the nine disciplines of the Eight Disciplines Problem Solving:

• D0: Preparation and Emergency Response Actions
• D1: Establish a Team
• D2: Describe the Problem
• D3: Develop Interim Containment Plan
• D4: Root Cause Analysis and Escape Points
• D5: Develop Permanent Solution
• D6: Implement Permanent Solution
• D7: Prevent Recurrence
• D8: Close Problem and Recognize Contributors

In comparison, here are the seven steps of the Toyota Practical Problem Solving (PPS), including the corresponding A3 sheet.

• Clarify the Problem
• Break Down the Problem
• Set a Target
• Root-Cause Analysis
• Develop Countermeasures and Implement
• Monitor Process and Results
• Standardize and Share

Advantages of the 8D Problem Solving

These two processes have many similarities but also distinct differences. Both can be used, and of course you can adapt your own approach based on these two methods. But I see some advantages, or at least a stronger emphasis with the 8D problem solving.

Quick Reaction to Mitigate Damage

One of the great advantages of the 8D problem solving is its focus on quick reaction and damage mitigation! The whole 8D approach was born out of quality problems at Ford that killed people, and the idea to prevent death and also damages to the customer is very prevalent in the 8D problem solving. Before 8D does anything else, it does the discipline D0: Preparation and Emergency Response actions to prevent people from dying, as well as prevent major damage. Soon afterward, a similar discipline, D3: Develop Interim Containment Plan, also aims to minimize damages. Note that both are not (yet) a permanent solution (that comes in D6: Implement Permanent Solution), but merely a quick action to prevent further damages.

The first discipline D0 is probably the most expensive approach, but tries to prevent the worst damages. For example, if there is a possible flaw in a commercial airliner, this would be the equivalent of grounding the fleet. If the problem is a bit better understood, the fleet may fly again but be subject to frequent (and expensive) checks and verification to ensure they find occurrences of the problem before the plane drops out of the sky. This would be the discipline D3.  These actions are less expensive than grounding the fleet altogether, but may still hurt the bottom line in the long run and may be unsustainable. But they buy time until we find a permanent solution that is also financially viable in discipline D5 and D6.

Importance of the Team

A second advantage of the 8D problem solving is the focus on teamwork, albeit the advantage is not as pronounced as with the quick reaction. Both the first (after emergency responses) and the last disciplines focus on the team: D1: Establish a Team and D8: Close Problem and Recognize Contributors. For me, this gives a nice respect for people bracket around the whole 8D process. First, you pay attention in creating a team. Last, you recognize and value the contribution of the team and other contributions. Overall, a nice touch.

Of course, this does not mean that other problem-solving methods do not use teams. Of course they do. And, done well, the team creation at the beginning and valuing the contribution at the end are also part of the project. The only difference is that it is not spelled out explicitly, and hence may have less mental weight than with the 8D.

Escape Points

Another good element of the 8D is the escape points in D4: Root Cause Analysis and Escape Points (albeit they seem to be not in every 8D I have seen). Figure out why the problem was detected so late, and why the customer needed to tell you about your quality issue rather than your quality department figuring it out. While not needed for all problems, there are quite a few problems that benefit from understanding what allowed the defect or issue to „escape“ to the customer.

Weaknesses of the 8D Problem Solving

However, in my view there are also some weaknesses of the 8D problem solving. Like the advantages, these are not killer criteria, but rather slight weaknesses that can easily be worked around.

Problem Clarification

In the 8D problem solving, understanding the problem is the discipline D2: Describe the Problem. Done right, this is all you may need. However, I like the more thorough approach of the Toyota Practical Problem solving better, where you first clarify the problem, then break it down, and then set a target. Hence, the crucial step of understanding the problem has much more weight with the Toyota Practical Problem solving than with the 8D. The underlying methods are very similar, but the stringency at Toyota is better.

Implementation and Verification

The second weakness—and again it is not a strong flaw—is in implementation and verification. The disciplines D6: Implement Permanent Solution and D7: Prevent Recurrence feel a bit muddled. For me, core to any improvement is the PDCA (Plan, Do, Check, Act). This PDCA is also in the 8D problem solving, but it is not as pronounced as in the Toyota Practical Problem Solving. A common pitfall is skimping or skipping the „Check“ and „Act“ to see if the problem is truly solved, and to act if it is not. More emphasis on the „Check“ and „Act“ in the structure could help here.

At Toyota, there is an explicit step „Check“ with Monitor Process and Results, and an explicit „Act“ with Standardize and Share. For the 8D, this is also there, but a bit mushed together in D6: Implement Permanent Solution and D7: Prevent Recurrence. Again, not a big flaw, but I like the emphasis more at Toyota.

No A3 sheet?

Another minor weakness is the lack of an A3 sheet. While the 8D also has documentation, I like the summary and overview of the project on a single page. This makes it for me easier to understand and work on the project.

Of course, nobody stops you from using or adapting an A3 for the 8D problem solving, but it is not an inherent part of the 8D.

Summary

Both the Eight Disciplines Problem Solving and the the Toyota Practical Problem Solving are good tools to solve problems. Both have an underlying PDCA, which for me is essential. The strength and weaknesses are all pretty minor. If you use the Toyota way, nobody is stopping you from doing emergency actions at the beginning and having a containment plant shortly thereafter. Look for escape points if you want. Of course, at Toyota you also use a team. Similarly with the 8D, feel free to take as much time and effort as you need (and then some) to understand the problem. Make sure the „Check“ and „Act“ are done well regardless of the structure, and feel free to use an A3 (or adaptation thereof) if you like.

The 8D may be better for quality issues, with a focus on containment of the problem. The Toyota Practical Problem Solving is maybe a tad better for general process improvement with a focus on understanding the problem. However, there is no 8D police checking for the „correct“ use of the 8D, and many different companies and people—intentionally or not—modify the 8D for their use, often to improve it, sometimes to adapt it for their needs, and in some cases accidentally making it worse. Similarly, even within Toyota, the Toyota Practical Problem Solving has many different flavors and variants. Some people say the 8D is more for larger problems and the Toyota Practical Problem Solving is better for medium-sized problems, but I think either method can be adopted either way. (As for the small ones: Just do ‚em).

Hence, if you are familiar with the 8D and had success with it, keep on using it. Similarly, if the Toyota Practical Problem Solving helped you a lot, let it continue to help you. If you want to mash both of them together to include all the best parts, please do so (but make sure you don’t have too much excess overhead). Now, go out, solve your problems in any way that gives you results, and organize your industry!