What is the importance of statistics in quality control?

Answer 1

Your question is very general. I will try to answer it the best I can. As QC is usually taught in the universities (part of industrial engineering), there is typically a strong emphasis on the statistical aspects. However, in the industrial environment, as quality relates to human observation and error, the importance of statistics will depend on the product. If every product is inspected thoroughly, then the concepts of random sampling and acceptance-rejection criteria are not important. Quality control will focus on how to inspect, and spot defects. However, if inspection of every product is impractical, the inspections are done by sampling. In this case, knowledge of statistics is very important. Questions will arise on how many lots to inspect, and the criteria for acceptance and rejection. If too tight a criteria for acceptance is used, then many acceptable products will be discarded (Type I error). It too loose a criteria for acceptance is used, then many unacceptable productions will be sent to customers (Type II error).