Six Sigma Fail

3 and a half reasons that Lean Six Sigma fails to deliver

Why Lean Six Sigma fails to deliver

What is Lean Six Sigma?

Lean Six Sigma is a prescriptive methodology for improving flow and reducing variation in a process using data & process analysis techniques. More simply, it is a means to systematically improve the speed and quality of a process, and it is highly effective.

Sounds great, right? I mean who doesn’t want faster & better?

Well, I hate to be the bearer of bad news, but Lean Six Sigma is NOT a magic wand – faster & better isn’t always what is achieved.

I have worked with and around Lean Six Sigma for a number of years now and have observed wildly varying degrees of success in its utilisation. In some instances, the project delivers exactly what it set out to and the benefits in these instances are often significant; similarly, however, and perhaps even more frequently, I have observed the opposite.


In fact, I reckon that the majority of people that have had some exposure to Lean Six Sigma have experienced the latter. Why do I think that? Well if I had a quid for every time someone said to me something along the lines of “oh yes, we tried that once – it didn’t work”, I would be really quite wealthy.

So, what is the problem?

As is often the case, there are a great many things that can go wrong with a Lean Six Sigma project. Some of these ‘problems’ though are really common in my experience, see if you can spot a theme:

Focus on the wrong customer

One of the things that makes Lean Six Sigma effective is that part of the framework requires the practitioner to define the metric by which direction and success are gauged, and the metric is derived from the Voice of the Customer (VoC). What this means is the project focuses on the important stuff, as opposed to subordinating to the existing, often arbitrary, often inconsequential metrics.

At the same time though, many of the tools used such as a SIPOC would define a customer as the recipient of an output of a process step. This means that any party, internal or external that is downstream from where the process is triggered can be classified as a customer.

The potential issue here is that the practitioner derives a metric from VoC they’ve acquired internally and then proceed to work on improving that. What results is an improvement in that 1 area, but perhaps no improvement – sometimes even a detriment – from the perspective of the real customer.

This is an easy trap to fall into as the level of importance around an issue can be quite subjective. For example, I have seen a number of instances where a person has undertaken a piece of work to
streamline the process of dealing with customer complaints – a process which customers often care very little about – as opposed to working on the things that cause customers to complain in the first place.

In for a penny, in for a pound!

A defining characteristic of the Lean Six Sigma approach is the use of data. Data is used to size the problem, to measure the impact, to prove & disprove root causes, and to test the ultimate solution. The practitioner is a slave to the data.

This is a good thing; to almost quote former Netscape CEO Jim Barksdale: without data, all we have are opinions, and opinions can be very hit and miss. So using data to drive decision making through the project ensures that the decision making is sound.

Data can be a fickle friend though, and sometimes tells us things that we didn’t expect, sometimes it contradicts our opinions and quite often shows a level of significance considerably lower than what was expected – I have seen this many times; it happens.

The appropriate thing to do in these instances may be to just stop. Call it a day there and simply publicise that we were all wrong about just how big a problem ‘that’ was.

When this occurs though, I have observed a number of instances where the practitioner just ploughs ahead. Maybe they’re just committed to finishing what they started, maybe it’s a sunk cost mentality at work. I don’t know why it happens, I just know that it happens; and when the margin for improvement is considerably smaller than initially thought, the resulting condition can be a disappointment or even dissatisfaction at the overall impact of the project.

Predefined Solutions

By far the most common thing I have observed that practitioners do is to undertake a Lean Six Sigma project already having the solution in mind.

In the beginning, there are so many gaps in our understanding. As explained above, the approach aims to attain an understanding of the size and impact of the problem, and to prove with data what is causing the problem – if we don’t yet know these things how can we possibly know what the appropriate solution is?

The obvious answer here is we can’t (or if we did, then Lean Six Sigma is not the right approach – more on this shortly), so what follows is a process of box-ticking – working through the framework in order to appear to satisfy the requirements in order for the practitioner to justifiably implement the solution that they had thought of before starting to investigate the problem.

This really is pointless. Ultimately one of two things happen as a result, either a working solution is implemented, but much time has been spent unnecessarily ticking boxes, or worse, a suboptimal solution is implemented – at least the former results in a working solution!

This leads me on to…

The half

This is only half a reason, as it’s kind of just an extension of the last point.

Some people subscribe so heavily to Lean Six Sigma as an approach, that they apply it at every possible opportunity. The issue with that mentality is that it is not always the appropriate approach to use. Just like the above scenario where we already know what it is we are going to do, all of the investigation and analysis is a waste of time, unless we are open to having our minds changed. If not, if we are simply aiming for implementation then there are many more effective approaches available.

I have a socket set in my garage. It’s brilliant, and despite the cost, I have experienced no buyers remorse whatsoever. Contrary to my better half’s assertion at the time I bought it, I’ve used it loads of times and it never disappoints. If however, I used it to help the kids with their homework, I can’t imagine anyone would be as pleased with the results.

The sweet spot for the utilisation of Lean Six Sigma is where the cause and solution to a problem are unknown, the problem is measurable, and the means to measure and influence contributing factors are within our gift. Ultimately, Lean Six Sigma is like my socket set: perfectly designed for its intended use and infinitely less so for other applications.

The theme
Did you spot the theme?
Each of the issues covered above stem from faux pas made by the practitioner. Despite the often negative perception of the approach, almost all of the instances of a Lean Six Sigma project falling short have, in my experience, not been the result of a shortfall in the methodology.

A challenge then to all of those that assert its ineffectiveness: if a daydreaming commuter drives into the back of you at a roundabout, do you blame the car?