statistical_review

- The variance of a constant is zero.

- Adding a constant value, c to a variable does not change variance (because the expectation increases by the same amount).

- Multiplying a constant value, c to a variable increase the variance by square of the constant, c.

- The variance of the sum of two or more random variables is equal to the sum of each of their variances only when the random variables are independent.

and

- The covariance of two constants, c and k, is zero.

- The covariance of two independent random variables is zero.

When X and Y are independent. - The covariance is a combinative as is obvious from the definition.

- The covariance of a random variable with a constant is zero.

- Adding a constant to either or both random variables does not change their covariances.

- Multiplying a random variable by a constant multiplies the covariance by that constant.

- The additive law of covariance holds that the covariance of a random variable with a sum of random variables is just the sum of the covariances with each of the random variables.

- The covariance of a variable with itself is the variance of the random variable.

statistical_review.txt · Last modified: 2017/12/11 09:16 by hkimscil