The Institute for Government has called on ministers to be more transparent about they way make difficult infrastructure decisions.
In a new report, the Institute for Government said there also needs to be greater consistency across Whitehall departments to help the Treasury to prioritise between projects, particularly where the choice is between completely different options, like a transport project or an energy project.
It recommends that the Treasury and relevant departments publish clearer guidance for analysts, based on more and better data, with more consistent assessment.
The report adds cost benefit analysis is the best way for government to assess the economic value of projects, but it is often misused, inconsistently applied and poorly communicated.
The report argues that cost benefit analysis is sometimes used by ministers to justify decisions, which have already been made.
Not only does this erode public trust in government, it also harms the country’s long-term competitiveness, according to the think tank.
“Picking the right infrastructure projects can help boost productivity and economic growth,” said report author, Nick Davies.
“Cost benefit analysis should be a crucial tool for ministers making these decisions but too often it is misused, inconsistently applied and poorly communicated.
“Government must get much better at learning from the successes and failures of previous projects,” he added.
“Equally, ministers should be far more honest with the public about the limits of modelling and the real reasons behind their decisions. Cost benefit analysis is a useful tool but it will only ever be as good as the people using it.”