There are two main categories of Control Charts, those that display attribute data, and those that display variables data.
Attribute Data: This category of Control Chart displays data that result from counting the number of occurrences or items in a single category of similar items or occurrences. These “count” data may be expressed as pass/fail, yes/no, or presence/absence of a defect.
Types of attributes control chart:
- p chart: This chart shows the fraction of nonconforming or defective product produced by a manufacturing process. It is also called the control chart for fraction nonconforming.
- np chart: This chart shows the number of nonconforming. Almost the same as the p chart.
- c chart: This shows the number of defects or nonconformities produced by a manufacturing process.
- u charts: This chart shows the nonconformities per unit produced by a manufacturing process.
Variables Data: This category of Control Chart displays values resulting from the measurement of a continuous variable. Examples of variables data are elapsed time, temperature, and radiation dose. While these two categories encompass a number of different types of Control Charts (Viewgraph 3), there are three types that will work for the majority of the data analysis cases you will encounter. In this module, we will study the construction and application in these three types of Control Charts:
- X-Bar and R Chart
- Individual X and Moving Range Chart for Variables Data
- Individual X and Moving Range Chart for Attribute Data
What Are the Control Chart Types?
Chart types studied in this module:
X-Bar and R Chart
Individual X and Moving Range Chart
– For Variables Data
– For Attribute Data
Other Control Chart types:
X-Bar and S Chart u Chart
Median X and R Chart p Chart
c Chart np Chart