Hi Jane.
Jim and I have gone back and forth on this topic. To start with, the 80% or 85% rule is a myth. Industrial engineering human factors engineering have proven this. This is my advanced engineering and statistics degrees' expertise. As I noted in a past post on this topic, some visual inspection systems can be 100% effective. It all depends on the factors cited in Maynard's Industrial Engineering Handbook. These include: work environment, part design, lighting, visual aids (magnification, light tables, profile templates & etc), and human factors such as job fatigue. Maynard also cites mental attitude. Note that the 85% myth evolved out of Vilfredo Pareto's 80/20 rule that 20% of plants generate 80% of the fruit and 80% of the land in Italy are owned by 20% of the population. This was never a universal truth. Applied to human performance, this rule is untenable. For example, in a visual inspection process, 20% of workers do not inspect 80% of the inspection results.
Jim and I have gone back and forth on this topic. To start with, the 80% or 85% rule is a myth. Industrial engineering human factors engineering have proven this. This is my advanced engineering and statistics degrees' expertise. As I noted in a past post on this topic, some visual inspection systems can be 100% effective. It all depends on the factors cited in Maynard's Industrial Engineering Handbook. These include: work environment, part design, lighting, visual aids (magnification, light tables, profile templates & etc), and human factors such as job fatigue. Maynard also cites mental attitude. Note that the 85% myth evolved out of Vilfredo Pareto's 80/20 rule that 20% of plants generate 80% of the fruit and 80% of the land in Italy are owned by 20% of the population. This was never a universal truth. Applied to human performance, this rule is untenable. For example, in a visual inspection process, 20% of workers do not inspect 80% of the inspection results.
