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WFM Glossary

WFM cycleWorkforce Management definitions and formulas

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Waiting Time

The time a call spends between entering the queue (often after a recorded message, or after having made a choice in a VRU) and an agent being connected to the call.

Weighted Mean

The weighted mean is similar to the general mean, except that some points contribute more to the mean than some others. Mathematically if we have a set of points \(a_n\) and a set of weights \(w_n\) that belong to the points, then the weighted average is equal to

\( WAV=\sum_{i=1}^{n}\frac{a_iw_i}{w_i} = \frac{a_1w_1 + a_2w_2 + \cdots + a_nw_n}{w_1+w_2+\cdots+w_n} \)

for example, if we have two sets of points, 1 2 with weight 1 and 3 4 5 with weight 2, then the weighted average of all points is equal to

\( \frac{1 \times 1+2 \times1+3 \times2+ 4 \times2+5 \times2}{1+1+2+2+2}=\frac{1+2+6+8+10}{1+1+2+2+2}=\frac{27}{8}=3.375 \)

In excel there are two ways to calculate the weighted average. say we have the values in column A and the weights in column B.

In the first method we set the product of A and B in column C. Then, the weighted average is given by WAV = SUM(C:C)/SUM(B:B)

The second method uses the sumproduct function. This method doesn't require an additional column to be used. WAV = SUMPRODUCT(A:A,B:B)/SUM(B:B)


Workforce Management consists of all activities from forecasting and planning to online control that have to do with the employment of agents in call center.

WFM Tool

A computer tool that assists planners with their WFM tasks. It minimally consists of forecasting, Erlang C, and agent scheduling modules.


Workforce Optimization includes WFM, call monitoring and agent performance management.


  1. The amount of hours that is required to handle offered or predicted workload. Because of the need for a safety margin, dictated by theory of variability, more workforce hours are needed than the amount of workload hours.
  2. Net Workforce: the amount of hours required to handle the amount of workload given a certain safety margin
  3. Gross Workforce: the total amount of hours that needs to be paid for.


Workload is defined as the amount of work in hours. Workload is usually calculated by the following formula:

\( Workload = Contact Volume \times Average Handling Time \)

Obviously the amount of offered and handled workload can differ over the same interval.

Wrap-up Time

Time after the end of a call that the agent spends on the call. Consist usually of entering call-related data in a computer system.