https://youtu.be/wPYYUvldKI8

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Y = f(x) is a key concept you must fully understand and remember. <b> </b>It is a fundamental principle to the Six Sigma methodology. In its simplest form it is called “cause and effect”. In its more robust mathematical form it is called “Y is equal to a function of X”. In the mathematical sense it is data driven and precise as you would expect in a Six Sigma approach. Six Sigma will always refer to an output or the result as a Y and will always refer to an input that is associated with or creates the output as an X.

Another way of saying this is that the output is dependent on the inputs that create it through the blending that occurs from the activities in the process. Since the output is dependent on the inputs we cannot directly control it, we can only monitor it.

For example, you can only measure or monitor the temperature (the Y) of an oven. If you want to affect it or control it you must adjust the amount of heat (the X) coming into the oven by adjusting the flow of gas or electricity by using the temperature control knob. Here you can begin to see that the temperature control knob is an input; that it is an independent action. If the temperature was too high and your food burned, the knob setting would be the cause of the problem. So The next time you would set the correct temperature to control the knob which is an input, to a lower temperature.

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