In this chapter, we’ll cover defects per million opportunities. This formula gives us the mathematical possibility that a process can be defective. It allows us to standardize defects at the opportunity level. And finally, it enables the comparison of complex processes from one to the other. For example, we might use defects per million opportunities for each step in a complex product or process to examine the aggregated risk of a defect. Or a defective, at the end of the process. This is similar to another formula, the rolled through yield of a process, but the formula is different. We add up the defect parts per million opportunities across each step of the process. Add them up, and then we compare the complex processes to each other, so that we can identify which processes need our immediate attention. There are three major components to defect per million. The DPMO calculation looks at opportunities for defects within the units that results in products or services that fail to meet the customer’s requirements and their performance standards. There are three key pieces that make up the DPMO calculation. It begins with the measurable failure or the defect being found. Then we would consider the unit, or the final deliverable. Whether it is a product or service that is impacted by the nature of the defects. Finally, we evaluate the opportunity that the attribute within the unit could result in a defect. Let’s apply DPMO to an example.
Consider the case of an electronics manufacturing company that creates tablets. We are going to examine how defects per million opportunities for the major sub-components, and how they roll up into the end product. So in the case of tablets, each individual tablet is considered a unit. And for the purposes of a DPMO calculation, the three major subcomponents are graphics capability, processing power, and battery life. These components represent opportunities for a defective tablet that does not meet the specifications, and what the customers expect. The first defect opportunity involves the sub-component of graphics. An example of the opportunity for the graphics to be defective could be that the tablet is not able to play video. Opportunity number two would be the processing ability. And an example of a defect might be that the tablet runs slowly. Or doesn’t run as fast as advertised. And finally, the third defect opportunity could be problems with the battery. This could mean that the tablet has a very low battery life, or does not meet the advertised specifications for performance. By combining all of these sub-components and their potential for defects, we begin to get a sense for the overall opportunity to have a failure in the tablet. If we go back and determine the defects per million opportunities in these three components, we can begin zeroing in on the one that’s the biggest culprit. And then proceed to the other ones that are less likely to fail.