Call Center

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Consider a Call Center process with unacceptable hold times, which might lead to a project to

reduce those hold times. A simple process map shows the process inputs, the core process

activity, and the output.

Much of the initial effort of a Lean Six Sigma project is to identify the X's (inputs), determine

which inputs (X's) are significant, and then quantify the relationship between those X's and Y

(output). Returning to the call center example, suppose that the process inputs, High Call

Volume and Low Staffing Levels, are believed to be the most likely causes of High Hold Times

for customers.

You may see this relationship expressed by the following general equation: Y=f(X), which means

output is a function of inputs. In other words, variability in the inputs causes defects, or errors,

in the output.

The transformation of Inputs by the process into an Output is represented by the Transfer

Function and the Transfer Function is shown in the Y=f(x) expression as the "f" or the function.

Understanding this transfer function is the first step toward resolving the root cause of a

problem at the source.

Errors (defects) cost money, and the cost compounds as items through any process, so

pushing higher capability (variability reduction) upstream to the source is the best ultimate

solution – offering the most sustainability and the lowest cost.

Think of the Lean Six Sigma DMAIC process as cleaning up a polluted river fouled by process

variability. Any of hundreds of tributaries may be the source(s) of the toxins.

Just as pollutants can undergo chemical reactions with other toxins and form new hazards,

variation propagates through a business process, creating increased levels of waste as errors

and defects compound.

The only way to eliminate the pollution (or variation) downstream is to find the sources

upstream and turn off the spigot. Identifying and resolving these upstream root causes of

variation (or defects) are the central activities of a Lean Six Sigma project.

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When a process is improved to the point that only 3 or less defects occur in each million

opportunities, the process is said to reach a Six Sigma Performance Level and achieving

significant improvement like that is what Lean Six Sigma is all about.