# What is the length of a sample over the length of the dataset

I need to refer to this quantity in a report, but I do not know what it is called. Basically if a dataset say:

$D = \{1,2,3,4,5,6,7,8,9,10\}$ has $10$ elements in total so $|D| = 10$ and I take a sample say: $S = \{1,3,4,10\}$, the sample has 4 elements so $|S| = 4$

What is $|S|/|D| = 0.4$ called? Is this named in a specific way in statistics?

Ted

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