Creating "Quality

Suppose 10 units are produced.
Assume that 7 of them are perfectly good, 1 is defective, and 2 are "gray" products that are difficult to judge.
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Here are two inspection devices.
(1) An inspection system that boasts a 90% yield rate
(2) An inspection system that can take out only "perfectly good" products, although the yield rate is 60%.
The former is used for inspection,
○○○○○○○△△△ and ×
are produced.
When inspected by the latter, the result is as follows,
○○○○○○ and ○△△×
The former appears to be superior to the latter at first glance, but the former is also judged to be better.
At first glance, the former appears to be superior, but in the former, the suspicious "△" is also judged as a good product, resulting in "outflow of defective products. If this is the case, it is necessary to "find two suspicious items out of nine and re-inspect them to determine whether they are good or bad. Since it is no longer necessary to re-inspect only one defective item, the labor-saving effect is 10%.
In the latter case, on the other hand, six of the items are "perfectly good" and can be shipped with peace of mind. Only the remaining 4 pieces need to be re-inspected. The labor saving effect is 60%. The re-inspection process is also much easier and less likely to result in the loss of defective products compared to the process of removing defective products from "○○○○○○○△△△△△".
However, it is possible to produce "quality" if only "complete good products" are taken out. It is said that "inspection equipment is a device that produces defective products and produces nothing," but if we change our way of thinking, it can be a device that "produces quality.