# The Six Sigma Approach:

Problem Solving with Y=f(x)

Y=f(x) is one of the most important aspects of the Six Sigma approach to problem solving. It will be critical that you understand this concept.

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Y refers to the measure or output of your process that you're measuring and trying to improve.

f(x) means "function of x". Combined, the statement is "Y is a function of x". Here is an example for a pizza delivery company that desires to meet customer expectations of on time delivery..

- Measure = On time pizza deliveries
- "Y" would be the percent of on time deliveries

- "f(x)" would be the x's or reasons or things that
heavily influence on time deliveries
- x1: traffic
- x2: # of delivery's en route
- x3: directions
- x4: reliability of delivery vehicle

The statement Y=f(x) in this example will refer to the proven x's determined through the steps of a Six Sigma project.

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This problem solving methodology takes you through the process of determining all potential "x's" that influence on time deliveries and then determining through measurements & analysis which "x's" are significant. Those will become the "x's" that are used in the Y=f(x) equation.

This problem solving strategy ensures that our pizza company does not spend $900,000 dollars on a GPS system for it's delivery vehicles when the root problem is not actually "directions".

The Y=f(x) equation is a very powerful concept and requires an ability to measure your output and quantify your inputs. Measuring process inputs and outputs is crucial to effectively determining the significant influences to any process.

The Six Sigma methodology walks you through the steps of defining your problem, your goal, your primary metric. Then, measuring your process, evaluating your measurement system, determining all possible x's etc.

The Six Sigma approach to problem solving leads you to the identification of the "critical" x's and from there establishing an improvement plan as well as a means to control & maintain your improvement. At the core of it all is the philosophy of Y=f(x).