The article discusses how to evaluate whether investing in airports is a good idea and how to choose between different airport projects. It looks at factors like revenue, benefits, expenses, uncertainty, and the rate of discount. It also considers indirect benefits and costs, the value of human life, and inflation. The researchers suggest rules for choosing a discount rate and handling uncertainty. They also talk about how to decide how much money to spend on uncertain projects and how to invest a fixed budget wisely. The importance of reinvesting is also highlighted.