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.
The Project Management Institute, however, endorses the accepted convention that a negative variance is a bad thing, and a positive variance a good thing. A variance is the difference between the projected budget and the actual performance for a particular account. A negative variance means that the budgeted amount was greater than the actual amount spent. A positive variance means that the budgeted amount was less than the actual amount spent. Note there is some debate over whether a negative variance means an underrun or an overrun.