The Value of Sequential Information

In decision analysis we normally consider the value of information to be a constant against which the cost of information is compared. However, when it is possible to buy information sequentially, the value of information is not a constant. Rather, it is a function of the prices of the various pieces of information, or “observables.” When we are faced with a decision and learn one observable, this information not only helps us make the original decision, but also helps us decide if we should pay for more observables. For this reason, the first observable has a value above and beyond that which we would assign if there were no possibility of obtaining additional information. To decide whether or not to buy one observable we must know the prices of all the observables.