MG 211 Lecture Notes - Lecture 15: Statistical Process Control, Control Chart, Central Limit Theorem
Document Summary
Objective provide a statistical signal when assignable causes of variation are present. Variability is present in every process: natural/common causes, special/assignable causes: detect and eliminate assignable causes of variation. If the distribution of outputs falls within acceptable limits, the process is in control. Can be traced to a specific reason. Objective to discover when assignable causes are present, eliminate bad causes, incorporate good causes. To measure the process, take samples and analyze sample statistics following these steps: samples of the product are taken off from the filling machine. They vary in weight: after enough samples are taken from a stable process, they form a distribution. Purpose distinguish between natural variations and variations due to assignable causes. For variables characteristics that can take any real value, may be in whole or fractional numbers, continuous random variables. Distribution of the sample means drawn from the population will follow a normal curve. Mean of sample = mean of population.
