Some purchasing specialist jobs also assign specialists to track the maintenance of office equipment. Maintaining records of warranties and service agreements is sometimes expected of a person in this position.
A retail price index would take this into account and use a weighted average which gives more prominence to commonly bought items. Excel does not contain a built in function to calculate a weighted average. It is however easy to do it using the SUMPRODUCT() function in a simple formula. SumProduct() multiplies two arrays (or ranges) together and returns the sum of the product. In the illustration it would calculate '(B4 x C4) + (B5 x C5) + (B6 x C6)'.
Weighted average, or weighted mean, is a method to compute a type of mean of a set of data in which different elements carry a different level of importance or weight. The most popular usage of weighted average is used in descriptive statistics, although the calculation is also used in various other areas of math. An extremely common example of the need for using a weighted average calculator is when grades are being calculated.