The UK government has a green book about estimating projects. Flupier worked with the UK Treasury and the Department of Transport in order to get this right. Other countries have studied this including Denmark and Denmark has also made this method mandatory. Basically, it's strategic misrepresentation in the opposite direction.
Whether it’s a giant infrastructure plan or a humble kitchen renovation, it’ll inevitably take way too long and cost way too much. That’s because you suffer from “the planning fallacy.” (You also have an “optimism bias” and a bad case of overconfidence.) But don’t worry: we’ve got the solution.