The Processes of Public Megaproject Cost Estimation: The Inaccuracy of Reference Class Forecasting

Governments worldwide are introducing “reference class forecasting” to improve the accuracy of megaproject cost estimation and thus ultimately the ability to deliver megaprojects on budget without altering the project specifications and/or changing the time schedule. In contrast to current findings, which show that reference class forecasting leads to more accurate project cost estimates by counteracting human cognitive and organizational biases, this article indicates the contrary, that reference class forecasting does not lead to more accurate cost estimates. The article theorizes that reference class forecasting fails to produce more accurate project cost estimates because estimates are always a relational network effect of human and nonhuman actors’ “biased” efforts to establish them. This finding challenges the existing literature by pointing to a more complex understanding of project cost estimation and biases. The finding is based on a longitudinal case study of a 23.6-billion-kroner Danish public megaproject, which failed to meet its objectives despite the application of reference class forecasting.