This may ruffle feathers of the Black Belts among you but I’m going to highlight an example to explain precisely why the majority of pragmatic clients aren’t interested in the upper levels that Six Sigma goes to. I’ve found through experience over the years that a client is more interested in building a continuous improvement culture involving everyone and through understandable means than knowing the equation to calculate the trajectory of Apollo13.
Call Center Astrophysics
Here’s a classic example, word for word, of a simple Call Center process improvement case through Six Sigma:
I need a help to solve this Six Sigma Case, for many it might be easy. Case: There is a Call Center process in which CTQ is Customer Response Time. If Customer Response Time is more than >60sec then its a defect. In this Case opportunity will be 1. Suppose there are 300 Calls and out of that 123 call Response time is >60 sec (This is defect) and opportunity is 1 then my Sigma value will be 1.727. This value came by this Formulae process Sigma = NORMSINV(1-((Total Defects) / (Total Opportunities))) + 1.5 and DPMO is 410000, this value came by this formulae Defects Per Million Opportunities (DPMO) = ((Total Defects) / (Total Opportunities)) * 1,000,000
Question is, Can anybody tell me from this case how can i get bell curve. How I should calculate USL and LSL value. How I will draw this Bell Curve in a excel. Waiting for all your master response.
A pragmatic response
I asked another BPM consultant on their take on the above, this was their response:
“…at the end of the day if you produce a bell curve telling me the USL and LSL for my call centre, along with the number of defects per million and a sigma value of 1.727, is this really a useful measure ?
More to the point, what can I – as a business person – do with it ?”
That last line is telling. Presented with information of this nature I would find it hard to glean anything useful in terms of process improvement to action. What’s more, turning a process into a set of calculations to eke the last drop of efficiency from it appears counterproductive.
The law of diminishing returns
There is an unwritten limit to continuous improvement that deems a point where the Law of Diminishing Returns starts to apply and no amount of incremental measurement to improve a process will yield significant return. Sadly where Six Sigma fails from a real world and pragmatic standpoint is that it doesn’t recognise that limit and will forever try to improve a process ad infinitum.
At no point in these improvement cycles and methods is there a step that says, “stop hacking the process to death and just start over from scratch”. Six Sigma becomes harder to sell and to explain the ROI when you reduce the cost efficiencies with each project to the point they become insignificant and the project more costly than the return. It becomes more about justifying the cost of running a team of Black Belts through cost savings than the efficiency of process because it improves the organization.
Starting afresh isn’t a bad thing
We need to teach organisations and Six Sigma practitioners that it’s not bad practice to throw something away entirely in order to achieve the greatest gains. We need to educate the leadership that wringing the last drop from a process out of some fierce Black Belt desire is wrong and that it’s ok to pick up the blank sheet of paper.
And we as a discipline and industry need to adopt the same approach for ourselves, that it’s ok to start over and create methods and tools that are context rich for today’s adaptive enterprise, not keep hold of the old ways because they form part of decades old tradition.
Continuous improvement is about adaptation. Given the rapid changes in business and technology around us Six Sigma is about the only thing that isn’t.