A genetic test examines the genetic information contained inside a person's cells, called DNA, to determine if that person has or will develop a certain disease or could pass a disease to his or her offspring.
Variance is non-negative because the squares are positive or zero. The variance of a constant random variable is zero, and if the variance of a variable in a data set is 0, then all the entries have the same value. Variance is invariant with respect to changes in a location parameter.That is, if a constant is added to all values of the variable, the variance is unchanged.ere Cov(â, â) is the covariance, which is zero for independent random variables (if it exists). The formula states that the variance of a sum is equal to the sum of all elements in the covariance matrix of the components.
Calculating variance allows you to measure how far a set of numbers is spread out. Variance is one of the descriptors of probability distribution, and it describes how far numbers lie from the mean. Variance is often used in conjunction with standard deviation, which is the square root of the variance.If you want to know how to calculate the variance of a set of data points, just follow these steps.alculating variance allows you to measure how far a set of numbers is spread out. Variance is one of the descriptors of probability distribution, and it describes how far numbers lie from the mean. Variance is often used in conjunction with standard deviation, which is the square root of the variance.