McGinnes, Simon

Conceptual Modelling: a psychological perspective

(2000)

This thesis is about psychological principles behind conceptual modelling, when practised during the design of typical business software application systems. The principles cover cognition (perception, memory, mental models) and group dynamics. Our purpose was to determine whether they could help make modellers more effective.

A critical analysis of existing methods was performed. A framework of psychological principles was developed and was used to analyse the design of an experimental modelling technique (method 'X'), consisting of a graphical modelling technique and a software tool for visual construction of models.

The effectiveness of method 'X' in real business situations was compared with that of more traditional object modelling. The results showed stark differences in performance for untrained modellers between the two techniques. Using object modelling, untrained modellers produced results that were grossly incomplete and incorrect (22-35% on average). Using the psychologically-inspired method 'X', untrained modellers produced models that were almost complete and correct (universally better than 82%).

For an expert modeller quality was uniformly high for both methods, but results indicate that expert modellers regarded the quality of method 'X' models as better and preferred method 'X' over the traditional approach. Significant differences in productivity were observed at all levels of expertise. On average, the expert modeller achieved productivity gains of approximately 150% with method 'X' over object modelling, and untrained modellers achieved gains of over 450%.

The results appear to support the idea of applying psychology to conceptual modelling. They suggest that modelling need not require a high degree of expertise, if methods and tools are adapted using current psychological knowledge. The results could be exploited to help untrained modellers, such as end users, who wish to develop or participate in the development of large software systems but lack access to the skills of trained IT professionals.

Supervisor: Professor James Backhouse, PhD

Simon McGinnes is currently a lecturer in the Department of Computer Science at Trinity College Dublin and Managing Director of CORAS in Dublin.

Dr. Simon McGinnes's personal web page.