Confidence of feedback information for improving quality.

In the semiconductor manufacturing industry, companies strive to improve product quality. One key to improved quality is having confidence in the feedback generated by production equipment. A study of the confidence level of feedback information was published in Engineering Applications of Artificial Intelligence (Vol. 26, 2013). At any point in time during the production process, a report can be generated. The report is classified as either “OK” or “not OK.” As an example, consider the following probabilities:

The probability an “OK” report is generated in any time period (t) is .8. The probability of an “OK” report at one time period 1t + 12, given an “OK” report in the previous time period (t), is .9. Also, the probability of an

“OK” report at one time period 1t + 12, given a “not OK”

report in the previous time period (t), is .5. If an “OK” report is generated in one time period, what is the probability that an “OK” report was generated in the previous time period?