Combination of Assessed Distributions

Future Population

Suppose you need information about the future population Metropolia City in the year 2020.  So you solicit two experts to provide assessments of this quantity and provide their expert judgments in the form of distributions as shown. Which assessment is better?  Who is right?  How can you combine these to arrive at a combined distribution that embodies the combined knowledge of both experts? The experts' distributions in this example are LogNormal(100K, 1.2), and LogNormal(90K,2). Calibration Arguably the most important criterion for judging a subjective assessment is for the source of that assessment (i.e., the expert) to be well-calibrated.   Calibration is a property of the assessor, not a property of a single assessment, and reflects the accuracy to which an expert can quantify his degree of uncertainty.   Being well-calibrated reflects the idea that over the course of many assessments, his assessed probabilities correspond to the empirical frequency of occurrence.  … [Read more...]