Question

Which is more useful for decision-making; variance or stamdatrd deviation? Why? What is the relationship between the two?

Answer 1

standard deviation is a more intutive measure of variance and defined as square root of variance, it is of superior nature of variability over the variance because it is measured in original units like dollars and any other measuring unit while variance is measured in squared units rather than orignal values.

The relationship between the standard deviation and variance is that variance as the average of the squared deviation from the mean while standard deviation is the square root of variance so we can say to calculate standard deviation we would need to calculate variance first.

Standard deviation is square root of variance