The purpose of control charts is to:
A)estimate the proportion of output that is acceptable.
B)inspect the quality of all outputs from a process.
C)determine if the output of a process is within specifications.
D)distinguish between random variation and assignable variation in a process.

Question

Quizplus · Accepted Answer

Control charts are used to distinguish between random variation (common cause variation) and assignable variation (special cause variation) in a process. The purpose is to identify when assignable variation is present so that it can be eliminated or reduced, leading to a more consistent and predictable process output that meets specifications. Option A is incorrect because control charts do not estimate proportions, they track process variations. Option B is incorrect because it is not feasible to inspect all outputs from a process. Option C is partially correct but incomplete - control charts determine if the output is within control limits based on statistical calculations, but these limits do not necessarily correspond to specifications.

The Purpose of Control Charts Is To