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It seems to me that some authors use different definitions on what is random and what is not? This confuses me so my question is which of these things are random variables.

  1. Data: does data refer to the actual measurements $x_1,\dots,x_n$ (realizations) or to the random variables $X_1,\dots,X_n$ that generated these values? For me both viewpoints are valid (present data and future data). However I saw the term data defined specifically for the non-random $x_1,\dots,x_n$.
  2. Population: is the population just a big quantity full of random variables $X_1,\dots,X_n$ where one takes out a sample $X_1,\dots,X_k$ for $k<n$ or is the population a giant set full of realizations from $X_1,\dots,X_n$?
kjetil b halvorsen
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Tensor
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  • Start with some of our posts on random variables, such as https://stats.stackexchange.com/questions/50. [Search our site](https://stats.stackexchange.com/search?q=+random+variable+population+score%3A10) for more. – whuber Jan 25 '22 at 15:45
  • @whuber I know what a random variable is. I come from probability theory. My question was regarding the terminology of the word data and population in statistics. Since for example in random matrix literature the statisticians seem to define data and the population as random while other literature does not. I don't understand why my question gets closed – Tensor Jan 25 '22 at 16:44
  • It was closed because your questions are answered in the duplicate thread. – whuber Jan 25 '22 at 16:54

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