# What does this simple notation mean?

$$X_{n:n}$$

where X is a random variable. Searched the internots but couldnt find anything

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Some authors use this to denote the largest order statistic in a sample of size n - in notation

$$X_{n:n} = X_{(n)}$$

is the largest order statistic.

You will also occasionally see this notation used in connections of double arrays of random variables, usually when a type of limit theorem is being discussed. (double array = arrangement of rows, with number of entries increasing with each row, to illustrate growing sample sizes)

There may be others.
In what context did you encounter this?

Some authors use this to denote the largest order statistic in a sample of size n - in notation

$$X_{n:n} = X_{(n)}$$

is the largest order statistic.

You will also occasionally see this notation used in connections of double arrays of random variables, usually when a type of limit theorem is being discussed. (double array = arrangement of rows, with number of entries increasing with each row, to illustrate growing sample sizes)

There may be others.
In what context did you encounter this?
Thanks a lot. I was using search term "rank statistic" instead of "order statistic".

This is in the context of largest insurance claim.