Abcdef

Why Large IT Projects Fail

Peter Henderson p.henderson@ecs.soton.ac.uk School of Electronics and Computer Science University of Southampton, SO17 1BJ, UK May 2006

Abstract Large IT projects may not deliver what they promise. Often they are late. Often they are over budget. Often what is eventually delivered is not either what was originally specified nor what is actually needed. There are many reasons why this happens. We discuss some of those reasons here and argue that many of them are a consequence of failure to specify requirements anything like adequately. We introduce the notion of requirements drift as a root cause of failure and show, by the use of models, that the often quite large discrepancies between expectations and reality can be the consequence of quite modest amounts of requirements drift. This preprint is available at http://www.ecs.soton.ac.uk/˜ph/LargeIT.pdf Keywords: Large IT Projects, Requirements, Failure, Open Systems, Complexity, Models

1

Introduction

Large IT projects are those that involve hundreds of software engineers and require many years to complete. Such projects often fail. Failure can be in various forms. Sometimes the delivered system fails to provide significant requirements to the standard of quality which makes it possible to actually deploy the system. Sometimes the anticipated cost for the project is exceeded by a large factor. Sometimes the anticipated delivery date is exceeded by a large factor. Often, failure involves a combination of all three of these effects. The main problem is to determine the causes of such failures, since this must precede the recommendations for mitigating their consequences. We will enumerate the accepted reasons for large project failure and show that an underlying cause of all of them is what we shall call requirements drift. The accepted reasons why large IT projects fail are many and various, but include all the following

1

Why Large IT Projects Fail -...