Class ImbalanceTherearetwomainreasonswhycertainclassesareunder-sampled.First,some categories (e.g., mixing) wish to remain unidentifiable due to the nature of their activities and thus apply privacy-enhancing schemes. For example, they obfuscate transactions through socalled peeling chains: a mixing service takes a customers’ deposits and moves it to one single address. Then, it starts sending very small amounts from this address to different services and the remaining coins (the change) to a new change address; this process is repeated until the very last coin has been spent.Table 7. Results from Prediction by Classes