An engineer uses 100 samples to check the average noise output of amplifiers (in Db) produced in the production line. If it is known that the line is normally distributed with standard deviation of th...

The previous section has introduced some statistical terms that are not widely used by engineers but are very familiar to statisticians. This section is a review of some of the statistical terms and p...

Example 5.1A manufacturing line produces resistors in a normal process with an average value of 500 ohms. A Sample of nine resistors were taken from yesterday^ production, with sample average = 540 oh...

The knowledge of certain properties of a subset (sample), can be used to draw conclusions about the properties of the whole set (populations). Properties can be of two types, as discussed in earlier c...

One of the concerns about using six sigma is the volume of production. There are two parts to this concern. The immediate reaction is that the 3.4 PPM defect rate associated with six sigma might imply...

Bad and good test effectiveness values are the percentage of PCBs that are properly distinguished as bad or good. This measure differs from test coverage, which is determined by the percentage of defe...

Test coverage (also called defect coverage) is a measure of the ability of a tester to detect defects. It is the percentage of those defects that are “covered” by a test，with 100% representing test co...

In the previous section, the in-circuit test was deemed the most important for achieving the six sigma level. As shown in Table 4.8, significant savings in cost could be achieved if this test method c...