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In general, uncorrelatedness is not the same as orthogonality, except in the special case where at least one of the two random variables has an expected value of 0. In this case, the covariance is the expectation of the product, and X {\displaystyle X} and Y {\displaystyle Y} are uncorrelated if and only if E [ X Y ] = 0 {\displaystyle ...
Then the random variables and are uncorrelated, and each of them is normally distributed (with mean 0 and variance 1), but they are not independent. [ 7 ] : 93 It is well-known that the ratio C {\displaystyle C} of two independent standard normal random deviates X i {\displaystyle X_{i}} and Y i {\displaystyle Y_{i}} has a Cauchy distribution .
A random variable with a Gaussian distribution is said to be normally distributed, and is called a normal deviate. Normal distributions are important in statistics and are often used in the natural and social sciences to represent real-valued random variables whose distributions are not known.
A ratio distribution (also known as a quotient distribution) is a probability distribution constructed as the distribution of the ratio of random variables having two other known distributions. Given two (usually independent) random variables X and Y, the distribution of the random variable Z that is formed as the ratio Z = X/Y is a ratio ...
In general, random variables may be uncorrelated but statistically dependent. But if a random vector has a multivariate normal distribution then any two or more of its components that are uncorrelated are independent. This implies that any two or more of its components that are pairwise independent are independent.
On the other hand, a negative correlation will further increase the variance of the difference, compared to the uncorrelated case. For example, the self-subtraction f = A − A has zero variance σ f 2 = 0 {\displaystyle \sigma _{f}^{2}=0} only if the variate is perfectly autocorrelated ( ρ A = 1 {\displaystyle \rho _{A}=1} ).
A more general case of this concerns the distribution of the product of a random variable having a beta distribution with a random variable having a gamma distribution: for some cases where the parameters of the two component distributions are related in a certain way, the result is again a gamma distribution but with a changed shape parameter ...
The generalized normal distribution (GND) or generalized Gaussian distribution (GGD) is either of two families of parametric continuous probability distributions on the real line. Both families add a shape parameter to the normal distribution. To distinguish the two families, they are referred to below as "symmetric" and "asymmetric"; however ...