In order for a project to be classified as successful, it must satisfy three criteria: its outputs must be of the agreed quality, they must be delivered in the agreed timescale, and they must be delivered at the agreed price.
The two studies below show that around a quarter of the software projects involved failed catastrophically (i.e. cancelled or delivered too late to be of use).
Furthermore, a significant number of projects in each study were challenged (i.e. they did not meet one or more of the criteria for success).
Figures that are worth bearing in mind when planning the scope of a new project.