Calculating Conditional Expectation for Continuous and Discrete Random Vectors

In summary, conditional expectation is a mathematical concept used to represent the expected value of a random variable given certain conditions or information. It is calculated using a formula that takes into account the probability of each possible outcome. The difference between conditional and unconditional expectation is that the latter does not consider any conditions or information. Conditional expectation is useful in making predictions and can be negative if the outcome has a low probability and a negative value. Both the sign and magnitude should be considered when interpreting its value.
  • #1
dror_l
1
0
Hi,

Let x,z continuous random vectors and n discrete random vector: n=[n1,n2,...].
I'm trying to find for instance, E_z|n3{ E_n|z(x)} = ?.

Thanks...
 
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  • #2
Can you explain your notation? Do you have two questions, E_z|n3 = ? and E_n|z(x) = ?
 
  • #3


Hello,

To calculate the conditional expectation for continuous and discrete random vectors, you will need to use the law of iterated expectations. This states that the expectation of a random variable is equal to the expectation of its conditional expectation, given another random variable. In other words, E[E(X|Y)] = E(X).

In your example, we have E_z|n3{ E_n|z(x)} = E[E_n|z(x)|n3]. This means that we first need to calculate the conditional expectation of E_n|z(x) given n3, and then take the overall expectation of this result.

To calculate E_n|z(x)|n3, we can use the conditional probability formula: P(A|B) = P(A and B)/P(B). In this case, we have E_n|z(x)|n3 = ∑x∫z P(z|x,n3)E_n|z(x)dz. This involves integrating over the possible values of z and summing over the possible values of n3.

Once we have calculated E_n|z(x)|n3, we can then take the overall expectation by summing over the possible values of n3, using the formula E(X) = ∑x P(x)X(x) for discrete random variables.

I hope this helps! Let me know if you have any further questions. Good luck with your calculations!
 

Related to Calculating Conditional Expectation for Continuous and Discrete Random Vectors

What is conditional expectation?

Conditional expectation is a mathematical concept used in probability theory to represent the expected value of a random variable given certain conditions or information.

How is conditional expectation calculated?

Conditional expectation is calculated using the formula E(X|Y) = ∑x(xP(X=x|Y)), where X and Y are random variables and P(X=x|Y) is the conditional probability of X given Y. This formula takes into account the probability of each possible outcome of X given the conditions of Y.

What is the difference between conditional expectation and unconditional expectation?

The unconditional expectation, also known as the average or mean, is the expected value of a random variable without taking any conditions or information into account. Conditional expectation, on the other hand, takes into account certain conditions or information and calculates the expected value accordingly.

What is the use of conditional expectation?

Conditional expectation is used in various fields such as economics, finance, and statistics to make predictions based on given conditions or information. It allows for a more accurate representation of the expected value of a random variable.

Can conditional expectation be negative?

Yes, conditional expectation can be negative. This occurs when the conditional probability of a certain outcome is low and the outcome itself has a negative value. It is important to consider both the sign and magnitude of the conditional expectation when interpreting its value.

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