T-Z

There are a lot of terms that are specific to Lean and Six Sigma. If you are unsure about the meaning of a term, please feel free to check our Lean and Six Sigma Glossary for a definition. If you do not find the term you are looking for, please contact us. We would be happy to answer your questions, and we may add your term to the glossary in the future.

Upstream

Processes (tasks, activities) occurring prior to the task or activity in question.

Value-adding activities

Steps/tasks in a process that meet all three criteria defining value as perceived by the external customer: 1) the customer cares; 2) the thing moving through the process changes; and 3) the step is done right the first time.

Value-enabling activities

Steps/tasks in a process enabling work to move forward and add value to the customer but not meeting all three of the value-adding criteria; should still be scrutinized for time and best practices-can it be done better?

Variation

Change or fluctuation of a specific characteristic which determines how stable or predictable the process may be; affected by environment, people, machinery/equipment, methods/procedures, measurements, and materials; any Process Improvement should reduce or eliminate variation. See also Common Cause; Special Cause.

Voice of the Customer, or VOC

Data (complaints, surveys, comments, market research, etc.) representing the views/needs of a company’s customers; should be translated into measurable requirements for the process.

X or Input

Variable used to signify factors or measures in the Input or Process segments of a business process or system.

Y

Variable used to signify factors or measures at the Output of a business process or system. Equivalent to “results.” A key principle of Six Sigma is that Y is a function of upstream factors; or Y = f(x).

Yield

Total number of units handled correctly through the process step(s).