EllipticEnvelope is a function that tries to figure out the key parameters of your data's general distribution by assuming that your entire data is an expression of an underlying multivariate Gaussian distribution. That's an assumption that cannot hold true for all datasets, yet when it does, it proves an effective method indeed for spotting outliers. Simplifying the complex estimations working behind the algorithm as much as possible, we can say that it checks the distance of each observation with respect to a grand mean that takes into account all the variables in your dataset. For this reason, it is able to spot both univariate and multivariate outliers.

The only parameter that you have to take into account when using ...

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