Is there a central limit theorem for Median?

In summary, there is a central limit theorem for the median under certain conditions. Specifically, if the model is F(x - \theta) and the population median is unique (F(0) = 1/2 and f(0) > 0), then the sample median will converge to a normal distribution with mean 0 and variance equal to 1/(4*f(0)^2) as n approaches infinity.
  • #1
grossgermany
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Homework Statement


Hi, We know the famous central limit theorem for means.
I wonder if there is a central limit theorem for Median?
If so under what regularity condition, does the median converge to a normal distribution with mean and variance equal to what?

Homework Equations





The Attempt at a Solution

 
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  • #2
One of the simplest results is this:
* Assume the model is [itex] F(x - \theta) [/itex]
* Assume both [itex] F(0) = 1/2 [/itex] and that the density [itex] f(0) > 0 [/itex]

(these assumptions mean the population median is unique)

Then the sample median satisifies

[tex]
\sqrt n \left(\hat \theta - \theta\right) \rightarrow n(0, \sigma^2)
[/tex]

in distribution, where the asymptotic variance is given by

[tex]
\sigma^2 = \frac 1 {4f^2(0)}
[/tex]
 

1. What is the Central Limit Theorem for Median and why is it important?

The Central Limit Theorem for Median is a statistical concept that states that as the sample size increases, the distribution of medians of samples from a population will approach a normal distribution. This is important because it allows us to make inferences about a population based on a sample, as long as the sample is large enough.

2. Is the Central Limit Theorem for Median the same as the Central Limit Theorem for Mean?

No, the Central Limit Theorem for Median and the Central Limit Theorem for Mean are two different concepts. The Central Limit Theorem for Mean states that as the sample size increases, the distribution of sample means will approach a normal distribution. However, the Central Limit Theorem for Median focuses on the distribution of medians instead of means.

3. Can the Central Limit Theorem for Median be applied to any type of data?

The Central Limit Theorem for Median can be applied to any type of data, as long as the sample size is large enough and the data is independent and identically distributed (IID). However, it is most commonly used with continuous data.

4. Does the Central Limit Theorem for Median hold true for small sample sizes?

No, the Central Limit Theorem for Median only holds true for large sample sizes. The rule of thumb is that the sample size should be at least 30 in order for the Central Limit Theorem to apply. For smaller sample sizes, other methods such as the bootstrap method may be more appropriate.

5. How does the Central Limit Theorem for Median relate to the Law of Large Numbers?

The Central Limit Theorem for Median and the Law of Large Numbers are related but different concepts. The Law of Large Numbers states that as the sample size increases, the sample mean will approach the population mean. This is a fundamental principle of probability and statistics. On the other hand, the Central Limit Theorem for Median focuses on the distribution of medians instead of means, and states that as the sample size increases, the distribution of sample medians will approach a normal distribution. In other words, the Central Limit Theorem for Median is a more specific application of the Law of Large Numbers.

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