[[Property:title|Elementary and composite metrics]]
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Some of our metrics will be elementary and some composite. An elementary metric is measured directly from the product or a project record:

{{definition|Elementary product metric, elementary process metric|<br/>
- An '''elementary product metric''' is a product metric whose values (integers) indicate the number of occurrences of a certain pattern in a product. <br/>
- An '''elementary process metric''' is a process metric whose values reflect measurements drawn directly from project records. }}

An example of elementary product metric is the number of source lines. An example of elementary process metric is the number of incremental compilations of a system.

Elementary metrics are provided by default by the metric tool. There is no means to remove them or to define new ones since they are not expressed as a combination of other metrics.

From these elementary metrics we may define composite ones:

{{definition|Composite metric|A '''composite metric''' is a metric whose values are defined by a mathematical formula involving other metrics (elementary, or previously defined composite metrics). }}
A later section will introduce a number of operations for defining composite metrics out of elementary ones. 
Again we may distinguish between product and process:

{{definition|Composite product metric, composite process metric|<br/>
- A '''composite product metric''' is a composite metric defined entirely in terms of product metrics. <br/>
- A '''composite process metric''' is a composite metric whose definition involves one or more process metrics. }}

By convention, this definition treats as process metric as a composite metric involving both product and process components.

The classification introduced for metrics extends to measures, so that we may talk about an elementary product measure, a composite process measure and so on.

{{seealso|<br/>
[[Attributes, metrics and measures|Metrics]]  <br/>
[[Scopes|Scopes]]  <br/>
[[Domains|Domains]]  <br/>
[[Selection Criteria|Selection criteria]]  }}




