Elementary Structures in Entity-relationship Diagrams as a Diagnostic tool in Data Modelling and a Basis for Effort Estimation

Elsewhere Kennedy describes three elementary structures to be found in entity-relationship diagrams. Here, each of these structures is considered in the context of a transaction processing system and a specific set of components that can be associated with the structure is described. Next, an example is given illustrating the use of elementary structures as an analytical tool for data modelling and a diagnostic tool for the identification of errors in the resulting data model. It is conjectured that the amount of effort associated with each structure can be measured. A new approach for the estimation of the total effort required to develop a system, based on a count of the elementary structures present in the entity-relationship diagram, is then proposed. The approach is appealing because it can be automated and because it can be applied earlier in the development cycle than other estimation methods currently in use. The question of a suitable counting strategy remains open.