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What is the definition of bell-shaped curve?

A graph of variable data characterized by a high center, tapered sides, and bell-flared edges. A bell-shaped curve reflects conditions that exhibit natural variation.

Learn more about bell-shaped curve in the class "SPC Overview 210" below.

SPC Overview 210

Quality Department

Class Information

Tooling U classes are offered at the beginner, intermediate, and advanced levels.
The typical class consists of 12 to 25 lessons and typically requires at least two hours of instruction time.

Class Name	SPC Overview 210
Description	This class describes the main concepts of statistical process control and explains how to recognize processes that are affected by special causes. Includes an Interactive Lab.
Prerequisites	800220 900100
Difficulty	Intermediate
Number of Lessons	16

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Class Outline

Class Objectives

Objectives

The Definition of Quality

Key Quality Characteristics

Definition of SPC

Common Causes and Special Causes

Control Charts

Control Limits

The

Chart

Average Sample Size

The R Chart

The P Chart

Process Capability vs. Process Control

The In-Control Process

The Out-of-Control Process

Process Improvement

Summary

Describe how customer demands relate to product specifications.

Define key quality characteristic.

Define statistical process control.

Distinguish between common causes and special causes.

Describe the purpose of a control chart.

Describe the purpose of control limits.

Describe the general appearance of an

chart.

Distinguish between the effects of variation on individual measurements and sample averages.

Describe the general appearance of an R chart.

Describe the general appearance of a P chart.

Distinguish between process capability and process control.

Identify a process that is in control.

Identify signs that a process may be out of control.

Describe how statistical process control leads to process improvement.

Class Vocabulary

Term	Definition
attribute data	Data that represents the absence or presence of characteristics. Go/no-go gaging or the presence/absence of a component yield attribute data.
bell-shaped curve	A graph of variable data characterized by a high center, tapered sides, and bell-flared edges. A bell-shaped curve reflects conditions that exhibit natural variation.
centerline	The horizontal line on a control chart that represents the average for a process.
common cause	A source of variation that is normal and expected. Common causes are predictable over time and yield a normal distribution.
control chart	A graph used during SPC efforts that charts data and provides a picture of how a process is performing over time.
control limit	A horizontal line on a control chart that represents a boundary for a process. If the process strays beyond a control limit, it is out of control.
external customer	An organization or individual that receives a product or service from the company.
grand average	The average of sample averages. The grand average is the centerline on an X bar chart.
internal customer	A department or individual within the company that relies on others to satisfy the external customer.
key quality characteristic	A measurable characteristic of a product that greatly impacts customer satisfaction. Key quality characteristics are the focus of SPC efforts.
lower control limit	A control limit indicating the boundary for the minimum permissible values.
micrometer	A U-shaped measuring instrument with a threaded spindle that slowly advances toward a small anvil. Micrometers are available in numerous types for measuring assorted dimensions and features.
natural variation	Variation resulting from sources that are normal and expected. Natural variation is predictable over time.
normal distribution	Variable data that clusters about an average and is symmetrical. When graphed, a normal distribution appears as a bell-shaped curve. In-control processes yield a normal distribution.
P chart	The control chart that tracks the percentage of nonconforming items. A P chart is used with attribute data.
process capability	The total range of variation within a process, including common and special causes.
process control	The range of variation within a process after special causes have been eliminated.
processes	A set of activities that uses resources to transform inputs into outputs. Essentially, a process describes the way "things get done."
quality	The satisfaction of customer requirements. Quality products conform to specifications, are free of defects, and meet the requirements of its anticipated use.
R chart	The control chart that tracks sample ranges over time. An R chart is used with variable data.
sigma	A unit of standard deviation indicating the degree of spread within a set of measurements.
special cause	A source of variation that causes a fundamental change in a process. Special causes distort a normal distribution and are undesirable.
statistical process control	The use of statistics and control charts to measure key quality characteristics and control how the related process behaves. SPC separates special causes of variation from common causes.
statistics	The science of collecting, summarizing, and analyzing numerical data. Statistics makes it possible to predict the likelihood of events.
tolerance	A blueprint specification indicating an unwanted but acceptable deviation from a given dimension.
unnatural variation	Variation resulting from one or more sources that involve a fundamental change in a process. Unnatural variation is undesirable.
upper control limit	A control limit indicating the boundary for the maximum permissible values.
variable data	Data that contains a range of quantities. Most measurements yield variable data.
variation	A difference between two or more similar things.

What is the definition of bell-shaped curve?

A graph of variable data characterized by a high center, tapered sides, and bell-flared edges. A bell-shaped curve reflects conditions that exhibit natural variation.Learn more about bell-shaped curve in the class "SPC Overview 210" below.

SPC Overview 210

Quality Department

A graph of variable data characterized by a high center, tapered sides, and bell-flared edges. A bell-shaped curve reflects conditions that exhibit natural variation.

Learn more about bell-shaped curve in the class "SPC Overview 210" below.