Electronic Card Assemblies. In a 1995 article in Quality Engineering, Ermer and Hurtis discussed applications of control charting to the monitoring of soldering defects on electronic card assemblies. One assembly technology they studied was pin-in-hole (PIH) technology, which uses wave soldering to secure components to printed circuit boards after the leads of components have been inserted through holes drilled in the boards. The most common types of soldering defects encountered using this technology are "shorts" (unwanted electrical continuity between points on an assembly) and "opens" (the absence of desired electrical continuity between points on an assembly). Production of a particular card is done in "jobs" consisting of 24 cards. All cards from a job are tested, and a count is made of the total number defects found on the job. What type of probability model might plausibly be used to describe the number of defects found on a given job? What type of control chart might you use to monitor the production of soldering defects? Suppose that records on 132 jobs show a total of 2 defects recorded. What retrospective control limits might then be applied to the 132 different counts of defects? Does a job with any defect at all signal a lack of control?