Considerations for Data Modeling 
You can create the aspects in EC-EIS and EC-BP according to your information requirements and volume of data. Data which belongs together from a business perspective and which has common objects of reference should be combined in a single aspect.
In order to carry out cross-aspect analyses, you can define view aspects in EC-EIS. These consist of the characteristics and basic key figures of interest chosen from as many aspects as you wish. EC-EIS reports are always based on one aspect or one view aspect.
During the data modeling phase you need to consider carefully the level of detail required for the data within EC-EIS and EC-BP. A greater level of detail in the data simplifies specific searches during navigation and drilldown in presentation and also allows more detailed planning. However, the greater volume of data required will increase response times. You need to decide here, to which degree the data transferred from transaction systems can be usefully aggregated.
In general in the system, and also therefore in EC-EIS and EC-BP, there is a strict separation of master data and transaction/plan data. Master data includes, for example, an enterprise’s customer list or product catalog. The master data in EC-EIS and EC-BP is managed in its own tables, independent of the aspects. The aspect tables contain transaction data and/or plan data only.
See also:
For information on maintaining an aspect, see Creating an Aspect.