ABSTRACT
P charts are used for proportions of nonconforming or defective product units found in a sample lot. For example, in a lightbulb manufacturing plant during final inspection, what percentage of lightbulbs did not light up from a randomly selected production sample lot? Another P chart example can be for proportion of sales orders with errors to total number of sales orders processed in a week. One more P-chart example can be for proportion of airplanes that arrived late in a 24-hour day to total number of airplanes arrived. A product unit can be inspected for one or more attribute characteristics during an inspection. Sample lot sizes for P charts can be a constant or can vary.
