Most SE methods proposed, give structure to the products; it is claimed that structure makes them easier to understand, analyze, and test. This is an example of the intuitvely appealing but rarely established connection: "good internal structure leads to good external quality".
A major reason that developers want to use internal attributes to predict external ones is the need to monitor and control the products during development (eg. internal design ---> failures).
For composite measures, i.e., measures depending on several other measures it is hard to arrive at an objectively correct scalar measure. This is a problem for many external attibutes like size, quality, and complexity.
For resources likely candidates for measurement are personnel (individual or team), materials (eg. office supplies) and methods (tools and techniques).
Cost is measured across all types of resources for use of management. Attributes for personnel include productivity, experience, age, and size, structure, communication pattern of teams. Attributes of methods may be language type, automatic or manual etc.