ComputerWeekly: A study published by Oxford University's Said Business School finds that major IT projects are 20 times more likely to fail than other IT projects. On average, larger IT projects ran 27 percent over-budget and took 55 percent longer to complete than originally planned. However, some major projects, referred to in the report as "black swans," spin dramatically out of control. These projects cost 197 percent more than planned and take 68 percent longer than planned.
According to the report, the reason for many of the failures is that IT managers ignore unpredictable events when they are planning and instead focus on the average performance of previous IT projects. The study authors also found that software projects were more likely to run over budget than hardware projects because the scope of these projects was likely to change after initial approval.