A survey of 60 MIS directors revealed that the biggest cause of failures on software projects was the choice of methodology. The other causes, in ranked order, were 2) lack of customer involvement, 3) lack of formal project management practices, 4) dissimilarity to previous projects, 5) project complexity, and 6) requirements volatility.

The companies surveyed had average revenues of $58 million and employed 370 people on average. From the answers the directors gave, it seems to me that these companies use heavier processes. They want formal project management practices and static requirements.

In an argument for agile, one might realize that agile addresses many of these concerns. If agile is a fit for your team, it involves customers (increased feedback with customers in warrooms), reduces complexity with small releases (short monthly iterations), and reduces requirements volatility with incremental releases (for example, in Scrum the sprints have no scope creep - new code goes in the next sprint.)

Relating back to the post yesterday, perhaps the weight of the process is not the variable which affects project success; perhaps it is the fit of the methodology to the project.

"While the raging debate about methodologies assumes that one methodology is inherently superior, such judgments are unwarranted without consideration of the project context in which the methodology is applied. It is not the chosen methodology per se that drives project risk but how well it fits a given project." P.74

Tiwana, A. & Keil, M. (2004). The one-minute risk assessment tool. Communications of the ACM, 47(11), 73-77. (PDF)