Which one should we choose while counting defects and calculating sigma level of a project - DPM or PPM , can we take either of the two ??

 

Good question, Inderjeet.

Generally, DPM (defects per million) is a preferred approach as PPM (Parts per million) corresponds to defectives per million. Defects data is considered more useful and powerful for process owners. At the same time customers may be concerned about PPM, as it is the defectives that affect them.

If you look around in automotive component manufacturing, many companies initially target 100 PPM for a part that has not yet reached a high process maturity level. It is important to visualize that DPM ensures a stricter and safer approach and 100 DPM is more difficult to achieve than 100 PPM.