Overview of the ProcessControl Package
Control Charts for Attributes
Control Charts for Variables
The Floating-Point Environment
The ProcessControl package provides a number of statistical control charts as well as tools for computing control limits for these charts.
Each command in the ProcessControl package can be accessed by using either the long form or the short form of the command name in the command calling sequence.
Because the underlying implementation of the ProcessControl package is a module, it is also possible to use the form ProcessControl:-command to access a command from the package. For more information, see Module Members.
Control charts for attributes allow you to visualize quality characteristics that cannot be represented in numeric form. In such cases, all items are subdivided into two categories: conforming or nonconforming to the specification of this quality characteristic. The charts support procedures with constant and variable sample size.
The following is a list of available commands.
Generate the C chart
Compute control limits for the C chart
Generate the NP chart
Compute control limits for the NP chart
Generate the P chart
Compute control limits for the P chart
Generate the U chart
Compute control limits for the U chart
To display the help page for a particular command, click the corresponding link in the table, or enter ?ProcessControl[command_name] at the Maple prompt.
Control charts for variables allow you to visualize quality characteristics that can be represented in numeric form. The charts support procedures with constant and variable sample size.
Generate the EWMA chart
Compute control limits for the EWMA chart
Generate the MA chart
Compute control limits for the MA chart
Generate the MR chart
Compute control limits for the MR chart
Generate the R chart
Compute control limits for the R chart
Generate the S chart
Compute control limits for the S chart
Generate the X-bar chart
Compute control limits for the X-bar chart
Generate the X chart
Compute control limits for the X chart
Most ProcessControl package commands rely on external libraries that perform their computations in floating-point. These libraries include statistics and optimization routines provided by the Numerical Algorithms Group (NAG).
The routines used by the ProcessControl package use either the hardware floating-point environment or the arbitrary-precision software floating-point environment to perform the computations. To maximize efficiency, the solvers attempt to use hardware floats whenever possible. Software floats are used only when the environment variable UseHardwareFloats is set to 'false', or when UseHardwareFloats is 'deduced' and Digits is greater than the value of evalhf⁡Digits.
A data set is generally provided as a Vector. Most ProcessControl commands accept an Array or a list in place of a Vector. For greatest efficiency, it is recommended that data sets be provided as Vectors of data type float.
Montgomery, Douglas C. Introduction to Statistical Quality Control. 2nd ed. New York: John Wiley & Sons, 1991.
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