O: "Solving Chi Square Problems: E(s^2) and Var(s^2) Using MLE

In summary, MLE (Maximum Likelihood Estimation) is used in solving Chi Square problems to find the most likely values for the parameters of a statistical model based on observed data. The expected value of s^2 is calculated using the formula E(s^2) = (n-1) * (σ^2), derived from MLE. E(s^2) and Var(s^2) both represent the expected value of s^2 but have different interpretations. Assumptions made when using MLE include a Chi Square distribution, random and independent sample, and large enough sample size. MLE can only be used for estimating the variance of a population and is commonly used in regression analysis and other statistical models.
  • #1
dim&dimmer
22
0

Homework Statement


[tex] W = \frac{vS^2}{\sigma^2}[/tex], distributed as [tex]X^2_v[/tex]
Find [tex] E(s^2) and Var(s^2)[/tex]

Homework Equations


[tex] E(W) = v , Var(w)=2v[/tex]

The Attempt at a Solution


Have been trying to figure this out with no luck. Can I use MLE for variance to show [tex]Var(s^2)= \sigma^2[/tex]? Really don't know how to get started on this, any pointers would be appreciated.
DIM
 
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  • #2
Remember that for any random variable [tex] X [/tex] and constant [tex] k [/tex]

[tex]
E(kX) = kE(X), \quad Var(kX) = k^2 Var(X)
[/tex]
 
  • #3
Thank you,
Sheesh, should have posted my question ...days ago, pretty simple really.
Dimmer.
 

1. What is the purpose of using MLE in solving Chi Square problems?

The purpose of using MLE (Maximum Likelihood Estimation) in solving Chi Square problems is to find the most likely values for the parameters of a statistical model, based on the observed data. In other words, MLE allows us to estimate the parameters that best fit the data, and therefore, make more accurate conclusions about the population being studied.

2. How is the expected value of s^2 calculated using MLE?

The expected value of s^2 (E(s^2)) is calculated using the formula E(s^2) = (n-1) * (σ^2), where n is the sample size and σ^2 is the variance of the population. This formula is derived from the MLE method, which aims to find the parameter values that maximize the likelihood of observing the sample data.

3. What is the difference between E(s^2) and Var(s^2) in MLE?

E(s^2) and Var(s^2) both represent the expected value of s^2, but they have different interpretations. E(s^2) is the expected value of the sample variance, while Var(s^2) is the variance of the expected value of the sample variance. In other words, E(s^2) is the average value of s^2 we would expect to obtain from multiple samples, while Var(s^2) measures the variability of this expected value.

4. What are the assumptions made when using MLE to solve Chi Square problems?

When using MLE to solve Chi Square problems, we assume that the data follows a Chi Square distribution, the sample is random and independent, and the sample size is large enough for the Central Limit Theorem to hold. Additionally, we assume that the data is continuous and that the parameters being estimated are fixed and not random.

5. Can MLE be used for any type of Chi Square problem?

No, MLE is specifically used for solving Chi Square problems that involve estimating the variance of a population. It cannot be used for other types of Chi Square problems, such as testing for independence or goodness of fit. MLE is most commonly used in regression analysis and other statistical models that involve estimating parameters.

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