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Contents | Index
Specification and Nominal values
When a file contains Variables data, the Analysis Options dialog box provides for entry of specification (customer requirements) limits and
nominal values. These values are:
- used to estimate capability indices. Only one specification value is required
for Cpk or Cpm indices. Both are required for Cp and Cr. The nominal value is
required for Cpm indices.
- shown on Process Capability and Individual-X charts when the Show Spec Lines
check box is enabled in the Chart Format Options dialog box. Specification
Limits are never shown on charts of averages (such as the X-bar chart), since the
specification applies to observations, and the distribution of the averages is
much narrower than the distribution of the observations.
High Spec: Enter the upper specification limit. This is the maximum value that you would
like the process to encounter. If you are using Short Run Options, you should
enter this value after Standardizing, so that it applies to all runs.
Low Spec: Enter the lower specification limit. This is the minimum value that you would
like the process to encounter. If you are using Short Run Options, you should
enter this value after Standardizing, so that it applies to all runs.
Nominal: Enter the desired target for the process. This value is only used in Cpm
calculations.
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