Data modeling in OBIEE using its Administration tools involves defining the physical layer, logical layer and presentation layer.

The Bottom-Up approach to Data Modeling for the OBIEE consists of importing the physical model first, then drag it across to the Business layer in the OBIEE Admin tool, and then to the Presentation layer.

The Bottom-Up approach which is the common approach is used when:

1. Already a fully denormalized star schema with joins, keys etc is ready.
   
2. The source is already an Essbase or other cube where the physical model contains all the multi-dimensional sources in a cube with summarized calculations for the dimensional hierarchies.

Although the most common approach is to start with the physical layer and then map it to the business model, you can consider the use of the alternate Top-Down approach.

To use the Top-Down approach, start with the business layer modelled as the enterprise data representation layer using the requirements of the business users. Here the Business layer is designed with the logical joins, logical PKs. The logical layer is then mapped to the Physical layer with thier PKs, FKs and physical joins. Then add the dimensions and calculations.

The advantage of this approach is that you can create a reusable business model that can be standardized for each vertical. If the physical layer does not support certain features of the business model, they can be altered or removed.

Whichever approach is used, it is a good practice to use business names in the Business Layer and the Presentation layer will automatically reflect this.