The dependent outcome variable of a process.

See also Y=f(X)


Pronounced "Y equals F of X", this means that some input parameters (X) affect the output (Y), so that if we change one of the input variables, we get a predictable change to the output variable, assuming all other factors remain unchanged. Most processes are governed by this transfer function.

Yamazumi Chart

A yamazumi board is a bar graph typically showing the balance of workloads as operator cycle times. The yamazumi can also be sued for load planning and scheduling. The word "yamazumi" literally means "to stack up".

Yellow Belt

A person who has gone through basic training to participate in a Lean / Six Sigma project.


A ratio calculated by dividing the number or volume good work pieces by the total number or volume of work pieces. Yield is expressed as a percentage. For example, if a process runs 100 pieces and 97 of them are good, the yield is 92%.


A Japanese term that loosely translates into “horizontal deployment.” Yokoten is the act of sharing improvements, lessons learned and insights across the organization. Not only are the results and benefits shared but also the process that led to the result, allowing others to copy and adapt.