The sum of all items divided by the number of items.

The average is calculated by dividing the sum by 'n' where n is the sample size. It is often used in statistics as interchangeable with the ‘arithmetic mean’ or ‘mean.’  

The advantage to utilizing the average is that it can be calculated for any set of numerical data, it is always unique, and it takes into account each individual item.

However, interpret averages with caution: a single extreme item can cause an average to skew the data and provide a result that is not typical or representative of the data. Consider calculating the weighted mean in addition to the average to ensure your interpretation of the data is correct.