 Legal probabilists have formulated different criteria for identifying the most appropriate reference class. Franklin (2011) is optimistic. On his approach, the most appropriate reference class for drawing an inference about an event or outcome \(B\) is the class defined by the intersection of all the features that are relevant to \(B\). Relevance is measured statistically given the available data as the co-variation of \(B\) with the feature in question. Co-variation will be measured using appropriate statistical criteria, such as the correlation coefficient between two variables. For instance, in the Shonubi case, features such as being Nigerian, drug courier, traveling toward JFK, were all relevant for making an inference about the total amount of drugs Shonubi carried. Other features for which data were available, such as being a toll collector at the George Washington Bridge, were not relevant. The optimism of Franklin’s approach, however, is dimmed by the pervasiveness of the reference class problem (for more details, see Hájek 2007).