What does this simple notation mean?

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Discussion Overview

The discussion revolves around the notation X_{n:n} in the context of statistics, specifically relating to random variables and order statistics. Participants explore its meaning, applications, and connections to rank statistics and insurance claims.

Discussion Character

  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant inquires about the meaning of the notation X_{n:n} for a random variable.
  • Another participant suggests that some authors use X_{n:n} to denote the largest order statistic in a sample of size n, equating it to X_{(n)}.
  • It is noted that this notation may also appear in discussions of double arrays of random variables, particularly in the context of limit theorems.
  • A participant mentions their initial search term "rank statistic" instead of "order statistic" and provides context related to the largest insurance claim.
  • A further clarification is provided that a "rank statistic" is based on the ranks of data, with the smallest value assigned rank 1, and that the theory of rank statistics can be expressed in terms of order statistics.

Areas of Agreement / Disagreement

Participants present multiple viewpoints regarding the notation X_{n:n}, with some agreement on its connection to the largest order statistic, but no consensus on its broader implications or definitions.

Contextual Notes

The discussion highlights the potential confusion between "rank statistic" and "order statistic," indicating that definitions and applications may vary among authors.

hassman
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[tex]X_{n:n}[/tex]

where X is a random variable. Searched the internots but couldn't find anything :frown:
 
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Some authors use this to denote the largest order statistic in a sample of size n - in notation

[tex] X_{n:n} = X_{(n)}[/tex]

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

[tex] X_{n:n} = X_{(n)}[/tex]

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.
 
A "rank statistic" is a statistic calculated based on the ranks of the data. The smallest data value has rank 1, the next smallest rank 2, and so on. Much of the calculation and theory (to determine distributions) of rank statistics can be expressed in terms of the order statistics.
 

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