Statistica Quality Control

In Chapter 5 we learned that total quality management (TQM) addresses organizational quality from managerial and philosophical viewpoints. TQM focuses on

customer-driven quality standards, managerial leadership, continuous improvement,

quality built into product and process design, quality identi?ed problems at the

source, and quality made everyone’s responsibility. However, talking about solving

quality problems is not enough. We need speci?c tools that can help us make the right

quality decisions. These tools come from the area of statistics and are used to help

identify quality problems in the production process as well as in the product itself.

Statistical quality control is the subject of this chapter.

Statistica1 quality control (SQC) is the term used to describe the set of statistical

tools used by quality professionals. Statistical quality control can be divided into three

broad categories:

1. Descriptive statistics are used to describe quality characteristics and relationships. Included are statistics such as the mean, standard deviation, the range,

and a measure of the distribution of data.

WHAT IS STATISTICAL QUALITY CONTROL?

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2. Statistical process control (SPC) involves inspecting a random sample of the

output from a process and deciding whether the process is producing products

with characteristics that fall within a predetermined range. SPC answers the

question of whether the process is functioning properly or not.

3. Acceptance sampling is the process of randomly inspecting a sample of goods

and deciding whether to accept the entire lot based on the results. Acceptance

sampling determines whether a batch of goods should be accepted or rejected.

The tools in each of these categories provide different types of information for use in

analyzing quality. Descriptive statistics are used to describe certain quality...