Quality and Process Methods • Process Capability
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Process Capability
Measure the Variability of a Process over Time
Process capability analysis, used in process control, measures how well a process is performing compared to given specification limits. A good process is one that is stable and consistently produces product that is well within specification limits. A capability index is a measure that relates process performance, summarized by process centering and variability, to specification limits.
Graphical tools such as a goal plot and box plots give you quick visual ways of identifying which process or product characteristics are within specifications. Individual detail reports display a capability report for each variable in the analysis. The analysis enables you to identify variation relative to the specifications or requirements; this enables you to achieve increasingly higher conformance values.
You can specify subgroups to compare the overall variation of the process to the within subgroup variation. You can compute capability indices for processes that produce measurements that follow various distributions. For data that follow none of the specified distributions, you can compute nonparametric capability indices.
Figure 10.1 Example of the Process Capability Platform
Contents 
Overview of the Process Capability Platform
Example of the Process Capability Platform with Normal Variables
Example of the Process Capability Platform with Nonnormal Variables
Launch the Process Capability Platform
Process Selection
Process Subgrouping
Historical Information
Distribution Options
Other Specifications
Entering Specification Limits
Spec Limits Window
Limits Data Table
Spec Limits Column Property
The Process Capability Report
Goal Plot
Capability Box Plots
Capability Index Plot
Process Capability Platform Options
Individual Detail Reports
Normalized Box Plots
Process Performance Plot
Summary Reports
Make Goal Plot Summary Table
Additional Examples of the Process Capability Platform
Process Capability for a Stable Process
Process Capability for an Unstable Process
Simulation of Confidence Limits for a Nonnormal Process Ppk
Statistical Details for the Process Capability Platform
Variation Statistics
Notation for Goal Plots and Capability Box Plots
Goal Plot
Capability Box Plots for Processes with Missing Targets
Capability Indices for Normal Distributions
Capability Indices for Nonnormal Distributions: Percentile and Z-Score Methods
Parameterizations for Distributions

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Help created on 7/12/2018