The standard deviation and variance are measures of the spread of a data set. Several measurements are used to provide the average of a data set, including mean, median, and mode.

The terms mean and average are often used interchangeably. The geometric mean redistributes not the sum of the values but the product by multiplying all of the individual values and then redistributing them in equal portions such that the total product remains the same.

geometric mean — a measure of center of a data set, calculated by multiplying the data values and then raising the product to the exponent 1 n , where n is the number of data values. standard deviation — a measure of the spread of a data set that indicates how far a typical data value is from the mean. variance — the measure of the spread of data values calculated as the square of the standard deviation. mode — the most frequently occurring data value in a data set.