 and thus the Bayes factor is greater than one if and only if the posterior probability \(\Pr(H \pmid E)\) is higher than the prior probability \(\Pr(H)\). The greater the Bayes factor (for values above one), the greater the upward shift from prior to posterior probability, the more strongly \(E\) positively supports \(H\). Conversely, the smaller the Bayes factor (for values below one), the greater the downward shift from prior to posterior probability, the more strongly \(E\) negatively supports \(H\). If \(\Pr(H)=\Pr(H\pmid E)\) the evidence has no impact, upwards or downwards, on the prior probability of \(H\).