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Do we have the numeracy for Six Sigma?

October 23rd, 2007 | By: Martin Arrand

There was a pretty depressing story in the Guardian a few days ago that proposes, in typical newspaper hyperbole, that Britain is in the grip of a numeracy crisis.

For once, the concern is justified. According to the article, there are 3 times as many UK adults with poor numeracy than poor literacy. That’s 15.1 million people with the equivalent of grade G or below at GCSE Maths (an appallingly low benchmark in any case).

What’s more, Tricia Hartley of the charity Campaign for Learning is quoted as saying:

“Many people in senior posts who are responsible for budgets, are really worried about their numeracy.”

As the article points out, there is a much greater social stigma attached to illiteracy than to innumeracy. Well-educated people are quite happy to admit that they were “never any good at maths”. I was surprised to find that senior, well-performing colleagues struggled in Six Sigma training because of their lack of mathematical competence. Those without degrees in science or engineering struggled most.

Six Sigma subtleties

Which brings me on to the supply chain angle in this story. One of the excuses people give for poor numerical skills is that, with computers and calculators, we don’t need to know much of the basic mathematics syllabus. The corollary for this in business would be that all of the “hard stuff” – the Six Sigma stats, or the forecasting algorithms – can be baked into systems and left to look after itself.

This represents a monumental missing of the point. Maths is not about how to do the mechanics of calculating a percentage or standard deviation – it’s the understanding of the application. Jane Imrie from the National Centre for Excellence in the Teaching of Mathematics makes my point for me”

“The problem when we talk about maths is that we talk about, ‘Can you add up, can you multiply, can you do this?’ We don’t ask, ‘Do you understand?'”

This ties in nicely with one of my favourite Lean slogans, attributed to Shingo Shigeo: “We have to grasp not only the Know-How but also ‘Know Why’”. (See the leanblog.org collection of Lean quotes.)

The point about Six Sigma is that it requires a reasonably high level of understanding of some fairly subtle mathematical concepts. In particular, it employs probability and statistics, topics that are probably most misunderstood by the general public (if they weren’t, casinos would go out of business).

I’m involved at the moment with helping Green Belt candidates choose appropriate projects. We are aiming to have all of our internal consulting team to Black Belt standard, but I’m starting to question whether that’s a realistic goal.

Not to rehash the Lean vs. Six Sigma debate…

At the same time I’m launching a Lean programme across one of the business units. There has been some Lean activity already, but there has yet to be an extensive and sustainable change towards a culture of continuous improvement.

I’m keeping the Six Sigma element of this fairly subtle, because I think its approach of using specialist experts works against the culture change goals – it encourages people to wait for the expert to come and improve their processes for them. Six Sigma will be useful in addressing systemic problems, as will a Factory Physics approach (which also requires considerable mathematical ability).

The other consequence of the specialisation inherent in Six Sigma is its focus on financial benefit: when you have a dedicated team of Black Belts, the business inevitably wants to see a return on this overhead. The temptation is a short-termist approach. Lean, by contrast, is something in which everyone can participate, and although it requires significant facilitation input it should (done rightly) produce ongoing benefits.


Pingback from Supply Chain View » More numeracy woes, bad news for supply chain skills
Time 7 November 2007 at 11:19 am

[…] read the MEN article, as it is very funny, if rather depressing. I wrote only last month about how poor numeracy threatens the success of Six Sigma. But failure at this level of simple arithmetical ability would make even the “keep it […]

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