Essential Biodiversity Variables (EBVs) have the potential to help stop species loss. An international research team is using an analogy to explain what these variables are. Just as the price of a share varies according to supply and demand and the prices of all individual shares are used to calculate the index of a stock exchange, data from observations of nature is used to calculate biodiversity variables. From these it is possible to calculate indices which are crucial to policy decisions. By using this analogy, the researchers aim to show how important EBVs are to the protection of biodiversity and where efforts in this area are being hampered by global gaps in our knowledge.