# Tag Info

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This is not generally true. While the empirical mean of the series is 2, the second moment of the process isn't necessarily equal to 2. This number is just a reasonable estimate of the mean if and only if the process is stationary and has a finite second moment. By subtracting 2 from the observations you would not necessarily get a mean zero series. You ...

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This operation is called de-meaning or more informally making the series/signal zero-mean. The "de-mean"ed version of $Y$ is surely $y=\{-1 -1,0,0,1,1\}$ as you wrote. But, this operation shouldn't be confused with the definition of zero-mean time series, i.e. a random process / signal is zero mean when $E[X(t)]=0$. You can make the signal zero-mean by ...

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Methods like k-means rely on a distance measure like the euclidean distance. The intention of the authors was probably to make the clustering problem on somewhat trivial data sets like iris harder by adding additional features, as you correctly assumed, that are not very discriminative with respect to the actual cluster structure in the data. How I ...

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