20 in images

MATLAB: An Introduction with Applications
6th Edition
ISBN:9781119256830
Author:Amos Gilat
Publisher:Amos Gilat
Chapter1: Starting With Matlab
Section: Chapter Questions
Problem 1P
icon
Related questions
Question

#20 in images.

Thank you

The text appears to be from a textbook on probability or statistics, dealing with conditional expectation and correlation coefficients. Below is the transcription suitable for an educational website:

---

### Conditional Expectation

**Find the correlation coefficient between \( Z \) and \( W \) and show that**

\[
0 \leq \rho^2 \leq \left( \frac{\sigma_1^2 - \sigma_2^2}{\sigma_1^2 + \sigma_2^2} \right)^2,
\]

where \( \rho \) denotes the correlation coefficient between \( Z \) and \( W \).

**19.** Let \( (X_1, X_2, \ldots, X_n) \) be an RV such that the correlation coefficient between each pair \( X_i, X_j, i \neq j, \) is \( \rho \). Show that \(- (n - 1)^{-1} \leq \rho \leq 1\).

**20.** Let \( X_1, X_2, \ldots, X_{m+n} \) be iid RVs with finite second moment. Let

\[
S_k = \sum_{j=1}^{k} X_j, \, k = 1, 2, \ldots, m+n.
\]

Find the correlation coefficient between \( S_n \) and \( S_{m+n} - S_m \), where \( n > m \).

*Note:* There is a handwritten note showing

\[
\rho = \frac{m - n}{n}.
\]

**21.** Let \( f \) be the PDF of a positive RV, and write

\[
g(x, y) = 
\begin{cases} 
\frac{f(x+y)}{x+y} & \text{if } x > 0, y > 0, \\
0 & \text{otherwise}.
\end{cases}
\]

Show that \( g \) is a density function in the plane. If the \( m \)th moment of \( f \) exists for some positive integer \( m \), find \( EX^m \). Compute the means and variances of \( X \) and \( Y \) and the correlation coefficient between \( X \) and \( Y \) in terms of moments of \( f \). (Adapted from
Transcribed Image Text:The text appears to be from a textbook on probability or statistics, dealing with conditional expectation and correlation coefficients. Below is the transcription suitable for an educational website: --- ### Conditional Expectation **Find the correlation coefficient between \( Z \) and \( W \) and show that** \[ 0 \leq \rho^2 \leq \left( \frac{\sigma_1^2 - \sigma_2^2}{\sigma_1^2 + \sigma_2^2} \right)^2, \] where \( \rho \) denotes the correlation coefficient between \( Z \) and \( W \). **19.** Let \( (X_1, X_2, \ldots, X_n) \) be an RV such that the correlation coefficient between each pair \( X_i, X_j, i \neq j, \) is \( \rho \). Show that \(- (n - 1)^{-1} \leq \rho \leq 1\). **20.** Let \( X_1, X_2, \ldots, X_{m+n} \) be iid RVs with finite second moment. Let \[ S_k = \sum_{j=1}^{k} X_j, \, k = 1, 2, \ldots, m+n. \] Find the correlation coefficient between \( S_n \) and \( S_{m+n} - S_m \), where \( n > m \). *Note:* There is a handwritten note showing \[ \rho = \frac{m - n}{n}. \] **21.** Let \( f \) be the PDF of a positive RV, and write \[ g(x, y) = \begin{cases} \frac{f(x+y)}{x+y} & \text{if } x > 0, y > 0, \\ 0 & \text{otherwise}. \end{cases} \] Show that \( g \) is a density function in the plane. If the \( m \)th moment of \( f \) exists for some positive integer \( m \), find \( EX^m \). Compute the means and variances of \( X \) and \( Y \) and the correlation coefficient between \( X \) and \( Y \) in terms of moments of \( f \). (Adapted from
Expert Solution
Step 1

It is an important part of statistics. 

It is very useful in all statistical procedures. 

steps

Step by step

Solved in 2 steps with 1 images

Blurred answer
Knowledge Booster
Reflections
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, statistics and related others by exploring similar questions and additional content below.
Similar questions
Recommended textbooks for you
MATLAB: An Introduction with Applications
MATLAB: An Introduction with Applications
Statistics
ISBN:
9781119256830
Author:
Amos Gilat
Publisher:
John Wiley & Sons Inc
Probability and Statistics for Engineering and th…
Probability and Statistics for Engineering and th…
Statistics
ISBN:
9781305251809
Author:
Jay L. Devore
Publisher:
Cengage Learning
Statistics for The Behavioral Sciences (MindTap C…
Statistics for The Behavioral Sciences (MindTap C…
Statistics
ISBN:
9781305504912
Author:
Frederick J Gravetter, Larry B. Wallnau
Publisher:
Cengage Learning
Elementary Statistics: Picturing the World (7th E…
Elementary Statistics: Picturing the World (7th E…
Statistics
ISBN:
9780134683416
Author:
Ron Larson, Betsy Farber
Publisher:
PEARSON
The Basic Practice of Statistics
The Basic Practice of Statistics
Statistics
ISBN:
9781319042578
Author:
David S. Moore, William I. Notz, Michael A. Fligner
Publisher:
W. H. Freeman
Introduction to the Practice of Statistics
Introduction to the Practice of Statistics
Statistics
ISBN:
9781319013387
Author:
David S. Moore, George P. McCabe, Bruce A. Craig
Publisher:
W. H. Freeman