Confronted with apparently difficult measurements, it helps to put the proposed measurement in context. Prior to making a measurement, we need to answer the following: 1. What is the decision this measurement is supposed to support? 2. What is the definition of the thing being measured in terms of observable consequences? 3. How, exactly, does this thing matter to the decision being asked? 4. How much do you know about it now (i.e., what is your current level of uncertainty)? 5. What is the value of additional information? In this chapter, we will focus on the first three questions.
