Subjective evaluation of Bayes factors

As we have mentioned above, and as we shall see later, not always the evaluation of updating factors can be done with the help of mathematical formulae like in the box example. However, we can make use of the virtual bet in this case too, remembering that a Bayes factor can be considered as the odds due a single piece of evidence, provided the two hypotheses are considered otherwise equally likely (hence, let us remember, the symbol $\tilde O$ used here to indicate Bayes factors).