Process Sigma.

Process Sigma: Sigma measures the standard deviation of a process's output, indicating how much variation or spread exists in the process performance. The higher the Sigma value, the smaller the variability and the more consistent and predictable the process is. Conversely, a lower Sigma value implies higher variability and a greater likelihood of defects or errors occurring.

How To Calculate the Sigma Level: 

1: Determine the number of units produced.

2: Determine the number of defect opportunities per unit.

3: Count the number of defects.

4: Calculate the DPMO using the formula.

                                     

                       DPMO = (#Defects)*(1000000) / (#Defecs Opportunity/unit)*(#Units)

• DPU or Defects per unit is the average number of defects observed when sampling a population.

                       DPU =  Defects / # of units

Process Sigma:

                                 PS= Normsinv (1-(D/O))+1.5

Example: