# What is variance?

The variance of a random variable is a measure of its statistical dispersion, indicating how far from the expected value its values typically are (Wikipedia 2006). The variance of a real-valued random variable is its second central moment, and it also happens to be its second cumulant (Wikipedia 2006). The variance of a random variable is the square of its standard deviation (Wikipedia 2006).

Variance is the difference between what is expected and the actuals. it is the difference between "should take" and "did take". The deviation from the actuals is called variance. Variance can be of two types positive and negative.

### What is a difference between a pooled variance and a combined variance?

Pooled variance is a method for estimating variance given several different samples taken in different circumstances where the mean may vary between samples but the true variance (equivalently, precision) is assumed to remain the same. A combined variance is a method for estimating variance from several samples, given the size, mean and standard deviation of each. Mathematically, a combined variance is equal to the calculated variance of the set of the data from all samples…

### Is the volume variance a controllable variance from a spending point of view?

No, the volume variance is controllable but not related to spending. The volume variance calculates the dollar impact of producing more or less than the budgeted production volume. No, the volume variance is controllable but not related to spending. The volume variance calculates the dollar impact of producing more or less than the budgeted production volume.

### Why would a favorable price variance for material might be the cause of unfavorable quantity variance?

A favorable/unfavorable price variance does not effect your quantity variance. The reason you would see a favorable price variance and an unfavorable quantity variance is because you consumed more materials than your standard allows AND the price you paid for those material was less than your standard price. If you paid more than your standard price, you would have experienced an unfavorable variance in both quantity and price.

### What is a positive or negative variance of a budget?

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. The Project Management Institute, however, endorses the accepted convention that a negative…