The consultant suspiciously eyed the c-chart that Chickenverks used to monitor the number of broken eggs in each 100 egg carton. "You know you really should be using a p-chart," the consultant commented with an air of superiority. "What's the difference between a p-chart and a c-chart in this application?" the long time Chickenverks employee asked with an obvious edge to his voice. "Well," the consultant replied, "the difference is:
A) the width of the three sigma limits for the c-chart is 100 times greater than those of the p-chart."
B) the three-sigma p-chart will catch problems earlier than the three sigma c-chart."
C) the three-sigma c-chart will catch problems earlier than the three sigma p-chart."
D) well, OK, you got me. The charts will look and behave the same for all practical purposes."

Question

Quizplus · Accepted Answer

The p-chart and c-chart essentially serve different purposes but can behave similarly in specific contexts. The p-chart is used for proportions (e.g., the proportion of defective items in a sample), while the c-chart is used for counts of defects per unit or sample (e.g., the number of defects in a batch). In the context of monitoring broken eggs in cartons, both charts could theoretically be used to track defects, and for practical purposes, their behavior in terms of detecting changes in the process may not significantly differ.

The Consultant Suspiciously Eyed the C-Chart That Chickenverks Used to Monitor