What is the variance of two independent variables?

What is the variance of two independent variables?

For independent random variables X and Y, the variance of their sum or difference is the sum of their variances: Variances are added for both the sum and difference of two independent random variables because the variation in each variable contributes to the variation in each case.

Who is responsible for materials price variance?

The materials price variance is usually the responsibility of the purchasing manager. The materials quantity and labor efficiency variances are usually the responsibility of production managers and supervisors. The materials price variance can be computer at what two different points in time?

What is variance in independent variables?

What is the product of two random variables?

A product distribution is a probability distribution constructed as the distribution of the product of random variables having two other known distributions. Given two statistically independent random variables X and Y, the distribution of the random variable Z that is formed as the product.

What are the properties of variance?

Basic Properties of the Variance. One useful result about variances which is relatively easy to show is that because the variance gives a measure or the square of the width of a distribution, the variance of a constant times a random variable is the square of the constant times the variance of the random variable.

How do you calculate the variance of a random variable?

For a discrete random variable the variance is calculated by summing the product of the square of the difference between the value of the random variable and the expected value, and the associated probability of the value of the random variable, taken over all of the values of the random variable. In symbols, Var(X) = (x – µ) 2 P(X = x)

Is variance and covariance related?

A covariance refers to the measure of how two random variables will change together and is used to calculate the correlation between variables. The variance refers to the spread of the data set-how far apart the numbers are in relation to the mean, for instance.