Big data may not know your name, but it knows everything else | Hacker News
1. All anonymisation algorithms (k-anonymity, l-divergence, t-closeness, e-differential privacy, (e,d)-differential privacy, etc.) have, as you can see, at least one parameter that states to what degree the data has been anonymised. This parameter should not be kept secret, as it tells entities that are part of a dataset how well, and in what way, their privacy is being preserved. Take something like k-anonymity: the k tells you that every equivalence class in the dataset has a size >= k, i.e. for every entity in the dataset, there are at least k-1 other identical entities in the dataset. There are a lot of things wrong with k-anonymity, but at least it's transparent. Tech companies however just state in their Privacy Policies that "[they] care a lot about your privacy and will therefore anonymise your data", without specifying how they do that.
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