Calculating Variances of Functions of Sample Mean

In summary, the asymptotic distributions for a) Y^2, b) 1/Y, and c) e^Y are as follows: a) Y^2 ~ N(u^2, (σ^4 + 2σ^2u^2)/n)b) 1/Y ~ N(1/u, V(1/X)/n)c) e^Y ~ N(e^u, V(e^X)/n) where Y is the sample mean of a random iid sample of size n with E(X) = u and V(X) = σ^2. The delta method can be used to determine the asymptotic variance, V(1/X) and V(e^X).
  • #1
Scootertaj
97
0
1. Essentially what I'm trying to do is find the asymptotic distributions for
a)
Y2
b) 1/Y and
c) eY where
Y = sample mean of a random iid sample of size n.
E(X) = u; V(X) = σ2

Homework Equations


a) [tex]Y^2=Y*Y[/tex] which converges in probability to [tex]u^2[/tex],

[tex]V(Y*Y)=\sigma^4 + 2\sigma^2u^2[/tex]

So, [tex]\sqrt{n}*(Y^2 - u^2)[/tex] converges in probability to [tex]N(0,\sigma^4 + 2\sigma^2u^2) [/tex]

So, [tex]Y^2\sim N(u^2,\frac{\sigma^4 + 2\sigma^2u^2}{n})[/tex]

Is that right?
b) [tex]\frac{1}{Y}[/tex] converges in probability to [tex]\frac{1}{E(X)} = \frac{1}{u}[/tex]
[tex]V(\frac{1}{x}) = \frac{1}{σ^2}[/tex] ??

Thus,
[tex]\sqrt{n}(\frac{1}{Y} - \frac{1}{u})[/tex] converges in distribution to [tex]N(0,V(\frac{1}{x})*\frac{1}{n})[/tex]
What is V(1/X) ?Am I on the right track?
 
Last edited:
Physics news on Phys.org
  • #2
Solved. Just had to remember the delta method.
 

1. What is the purpose of calculating variances of functions of sample mean?

Calculating variances of functions of sample mean allows for better understanding and analysis of data by measuring the spread or variability of a sample. It can also help in making predictions and estimating the precision of statistical estimates.

2. How do you calculate the variance of a function of sample mean?

The variance of a function of sample mean can be calculated by taking the squared difference between each observation and the sample mean, multiplying by the corresponding weight or probability, and then summing all the values. This can be represented by the formula: Var[f(x)] = E[(f(x) - E[f(x)])^2].

3. What is the relationship between sample size and the variance of a function of sample mean?

As the sample size increases, the variance of a function of sample mean decreases. This is because with a larger sample, the data points are more likely to be closer to the sample mean, resulting in a smaller spread or variability.

4. Can you provide an example of calculating the variance of a function of sample mean?

Sure, let's say we have a sample of 50 students and we want to calculate the variance of their test scores. We can take the square of the difference between each student's score and the sample mean, multiply it by the weight (1/50 for each student in this case), and then sum all the values to get the variance.

5. How can the variance of a function of sample mean be used in decision making?

The variance of a function of sample mean can be used to make informed decisions by providing information about the variability or uncertainty of the data. For example, a lower variance indicates a more consistent or accurate sample, whereas a higher variance may suggest a need for further investigation or data collection.

Similar threads

  • Calculus and Beyond Homework Help
Replies
5
Views
617
  • Calculus and Beyond Homework Help
Replies
1
Views
356
Replies
1
Views
622
  • Calculus and Beyond Homework Help
Replies
3
Views
644
  • Calculus and Beyond Homework Help
Replies
8
Views
873
  • Calculus and Beyond Homework Help
Replies
4
Views
685
  • Calculus and Beyond Homework Help
Replies
6
Views
756
  • Calculus and Beyond Homework Help
Replies
1
Views
702
  • Calculus and Beyond Homework Help
Replies
21
Views
836
  • Calculus and Beyond Homework Help
Replies
12
Views
1K
Back
Top