In some decision problems, an important consideration is the extent to which new information will reduce current uncertainty. A method that addresses this situation is called real-option analysis. Real-option analysis takes into account measures created or destroyed by pursuing given option. The method allows for the consideration of the benefits of keeping options open. In this sense, real option analysis is an extended net present value calculation, because it calculates not only the direct benefits of a measure, but also the benefits that may accrue in the future given climate change impacts and the ability, kept open by the measure, to adapt in the future. Consider the case of building a sea wall, and it is not known whether the expected level of sea level rise over the lifetime of the wall will be 50 or 100 centimetres, but it is expected that scientific study currently under way will reveal the correct answer within the next five years. One response might be to wait for this information before committing to a seawall of a particular height. At the same time, however, there may be a cost to waiting, because it will expose communities to a higher level of risk during that time. Calculating the cost of waiting is fairly easy, but calculating the benefits, essentially the value of leaving options open, can be more difficult. The practice of valuing options extends the furthest in financial markets, where analysts use a number of models, which relies on particular assumptions about market price movements and volatility. For other types of investments, such as adaptation projects, modelling the value of waiting can proceed on a more ad-hoc basis, as described in the case of the sea-wall (see Patt 2011).