About Critical to Quality Processing

Quality Metrics and Their Sources

Each metric has a different source: Goal, Predicted, Allocated, Measured, and Controlled. Only one metric with each source can be added to a CTQ, so there can never be more than 5 metrics. The order of the sources is important. Once a new metric is created with a certain source, previous source options can no longer be used. In other words, when a source option is skipped, then subsequent metrics can only be supplied from unused options that are after the current source value. For example, if a CTQ has only a Goal metric and then a new metric is created of source Measured, the subsequent metric must be of source Controlled.

• Goal. The first metric added to a CTQ. The goal metric's values are the target values that should be achieved by the end of the project. These are the values all other metrics for the CTQ are measured against.
• Predicted, Allocated, Measured. These are metrics that reflect the values at different phases in the process. These metrics do not have to be included in a CTQ, but if they are, they are added after the Goal.
• Controlled. The final metrics for the CTQ. When you add a Controlled metric, the system promotes the quality object to Controlled. A CTQ must have a controlled metric in order to be promoted to Controlled: the system generates an error if you try to promote the quality object when there is no Controlled metric.

Rules for Editing Metrics

• You can edit the goal metric at any point up until the CTQ is Controlled but you can never delete it. The goal metric's source cannot be changed.
• Aside from the goal metric, you can only edit and delete the last metric added.

For example, suppose a CTQ has three metrics: Goal, Predicted, and Allocated. At this point, only the Goal and Allocated metric can be edited. The Goal metric can always be edited before the CTQ is Controlled and the Allocated metric can be edited because it is the last metric added. Only the Allocated metric can be deleted. If you add a Measured metric, then the Allocated metric can no longer be edited or deleted but the Measured metric can be.

• Editing non-Goal metrics includes the ability to change the source to any other source that has not already been used. For example, suppose a CTQ has only these metrics: Goal, Allocated, and Measured. When editing the Measured metric, its source can be changed to Predicted or Controlled.
• When a Controlled metric is added (or an existing metric's source is changed to Controlled), the system promotes the Quality object to Controlled and no editing is allowed.

When the quality object is in the Controlled state, none of its metrics nor its attributes can be edited. So typically, Controlled metrics cannot be edited. The only condition under which a Controlled metric can be edited is if the quality issue is demoted to Initiated.

If a Controlled CTQ needs editing, the quality object can be demoted to Initiated. Then the previously-stated rules apply: the last metric added, which would be the Controlled metric, can be edited and deleted. The Goal metric can also be edited.

Steps in CTQ Processing

This section outlines the sequence of steps needed to process CTQs.

When creating CTQs and their metrics from scratch, as opposed to importing the information from a file, the basic steps are:

• Use the Create Quality wizard to create the quality object and the goal metric. For instructions, see Creating a CTQ.
• Add intermediate metrics as needed: Predicted, Allocated, Measured. These metrics are not required but once one of them is added only the subsequent metrics can be added. See Creating a Metric.
• Add the Controlled metric, which promotes the quality object to Controlled. See Creating a Metric.

When creating CTQs by importing from a file, you'll typically import both the quality object and the metrics for it. You can add to and edit the metrics according to the standard editing rules for metrics, described in About Critical to Quality Processing. If the Controlled metric is included in the import, the system promotes the quality object to Controlled and no editing is allowed.

However, if you import only the quality object, you'll need to add all metrics separately, including the goal metric. See Creating a Metric.

About Importing CTQs

By default, the import includes the following fields for quality and metric objects. Your system may be set up to access more or fewer fields and in a different order.

Follow these guidelines when creating the import file for CTQs:

• The file must be saved as a csv file, which is an ASCII text file with fields separated by commas.
• Multiple quality objects and multiple metrics for each quality can be imported in one file.
• If metrics are specified for a quality object, the first metric must have a source of Goal. It's best if the other metrics are in the correct source order but they don't have to be.
• There must an entry for each quality and metric field accepted by the import, and the fields must be in the order defined by the system administrator. The default fields and field order are listed in the above table. If a quality or metric does not have a value for a particular field, the file should just have two commas.
• The first field is always the type of the object to import.
• All dates must be in the format DD-Mon-YY, for example, 09-Sep-12.

Here is an example of an import file with fields for two quality objects, each with three metrics. The first has a continuous data type and the second is discrete.

Quality,Q-1820,Continuous,"Problem statement, is here",Operational 
definition,Defect Definition,Goal,Comments,Opportunity,Out Of 
Bounds,constraints

ContinuousMetric,QMet1821,Goal,1.342,0.89,1.2,1.9,1.2,Comments on the 
goal,

ContinuousMetric,QMet1822,Predicted,1.342,0.89,1.2,1.9,1.2,Comments on 
the goal,

ContinuousMetric,QMet1823,Controlled,1.342,0.89,1.2,1.9,1.2,Comments 
on the goal,

Quality,Q-1830,Discrete,"Problem statement, is here",Operational 
definition,Defect Definition,Goal,Comments,Opportunity,Out Of 
Bounds,constraints

DiscreteMetric,QMet1830,Goal,1,2,1.32,Goal comment,,,,

DiscreteMetric,QMet1831,Predicted,1,6,1.89,First Measure comment,,,,

DiscreteMetric,QMet1832,Controlled,1,3,1.4,"Controlled comment, 
done",,,,