Improvement Process and Transfer Function

We shall now discuss the Improvement Process and Transfer Function

Formula for transfer function is given by

Y=f(X)

Such that the transfer function is used to illustrate the concept that the important process outputs, (known as Ys), are a result of the drivers or inputs (known as Xs) within the process. This gives us our equation of Y=f(X). So now let’s take a look at the equation a little bit closer.

The equation shows that the output variable Y is dependent, such that its value depends on the value of X, where X is an independent-input variable and each X represents an input factor that determines or effects Y. And f indicates that there is a relationship between the two variables in which one variable depends on the other variable. The transfer function relates the inputs of a process to the outputs of the process such that within an organization or a department, a process has a measurable and therefore controllable output. This output from a process becomes input as it flows into the next level of the organization along with the output from other processes which enables departmental or organizational level outputs.

As a Six Sigma professionals we must try and understand the relationship between the Xs and the Ys and how the outputs of various smaller processes lead to organizational outputs. Thereafter this information can then be put into a functional graph that identifies the inputs, outputs, and processing tasks that are required to transform the inputs into the outputs.

X i.e., the input variable represent materials, information, and tasks that are accomplished by people using machines or equipment. Then comes the steps in processing which includes all tasks that are required to affect a transformation of the inputs into outputs. Finally comes Y i.e.,   outputs variable which includes the products, services, information, data, or material used in the next step of the process. Since every process within an organization has inputs and outputs which are arranged in such a manner that the output of one process becomes the input of the next process.

The key input variables are those key process inputs that have a strong potential to impact process outputs. Therefore it becomes crucial for the team members to have direct control over those key input variables. And when a change is made to a key input variable, it usually affects at least one key output variable, also referred to as the ‘Big Ys’. Where, these are any process outputs that fulfill or lead to the fulfillment of the Six Sigma deployment goals. Note, that there are usually fewer Big Ys than the key input variables, but there’s always at least one key output variable for each process. Also, the Big Ys may include very significant functional goals that directly influence an organization’s key objectives which relates to customers’ profitability, or efficiency, quality, and productivity. From this point of view, Big Ys are the most important for Six Sigma professionals.

The key output variables of those Big Ys are a result of the key input variables, the Xs within processes. The goal of Six Sigma is to identify which vital few input variables influence the desired output the most.