The construction of large software systems is one of the most hazardous activities of the business world. The failure or cancellation rate of large software systems is over 20 percent. Of the large systems that are completed, about two thirds experience schedule delays and cost overruns that may approach 100 percent. Large software systems cost far more to build and take much longer to construct than the office buildings occupied by the companies that have commissioned the software. Project failure is based on a handful of failed project case studies.