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The joint pdf () exists in the -plane and an arc of constant value is shown as the shaded line. To find the marginal probability f Z ( z ) {\displaystyle f_{Z}(z)} on this arc, integrate over increments of area d x d y f ( x , y ) {\displaystyle dx\,dy\;f(x,y)} on this contour.
If the points in the joint probability distribution of X and Y that receive positive probability tend to fall along a line of positive (or negative) slope, ρ XY is near +1 (or −1). If ρ XY equals +1 or −1, it can be shown that the points in the joint probability distribution that receive positive probability fall exactly along a straight ...
The fact that two random variables and both have a normal distribution does not imply that the pair (,) has a joint normal distribution. A simple example is one in which X has a normal distribution with expected value 0 and variance 1, and = if | | > and = if | | <, where >. There are similar counterexamples for more than two random variables.
Informally, the expected value is the mean of the possible values a random variable can take, weighted by the probability of those outcomes. Since it is obtained through arithmetic, the expected value sometimes may not even be included in the sample data set; it is not the value you would expect to get in reality.
Indeed, the expected value [] is not defined for any positive value of the argument , since the defining integral diverges. The characteristic function E [ e i t X ] {\displaystyle \operatorname {E} [e^{itX}]} is defined for real values of t , but is not defined for any complex value of t that has a negative imaginary part, and hence ...
The expected value or mean of a random vector is a fixed vector [] whose elements are the expected values of the respective random variables. [ 3 ] : p.333 E [ X ] = ( E [ X 1 ] , . . .
This sequence can be used to approximate the joint distribution (e.g., to generate a histogram of the distribution); to approximate the marginal distribution of one of the variables, or some subset of the variables (for example, the unknown parameters or latent variables); or to compute an integral (such as the expected value of one of the ...
MI is the expected value of the pointwise mutual information (PMI). The quantity was defined and analyzed by Claude Shannon in his landmark paper "A Mathematical Theory of Communication", although he did not call it "mutual information". This term was coined later by Robert Fano. [2] Mutual Information is also known as information gain.