A friend of mine sent the link to this useful and informative study. It is a must read to anybody who is planning to launch a new software project (not necessary online).
This article explores the reasons for these failures and reviews the questions to consider in improving your organization’s performance with large-scale software projects. Not surprisingly, considering these same questions will help you improve almost any large or small project with substantial software content. The principal questions concern why large software projects are hard to manage, the kinds of management systems needed, and the actions required to implement such systems.
The conclusion is… well, the best if you read the full article. It will make more sense.