WFM Glossary

Workforce Management Terminologies, definitions, formulas and Erlang calculators!

Erlang Calculator click here

Two-Skill Calculator click here

Calculators Gerkoole.com click here

Browse the glossary using this index

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | ALL

A

After Call Work

See wrap-up time

AHT

Average Handling Time, the time agents spend on average on a service request, usually a call, an email or a chat. The wrap-up time is also included. See also handling time.

B

BPO

Business process outsourcer, a company offering call center services, often to multiple organizations at the same time, regularly from a cheaper off-shored location such as India or the Philippines.

C

Call Center Arithmetics

Basic WFM calculations based on totals and averages, without taking fluctuations and flexibility into account. See also call center mathematics.

Call Center Mathematics

Advanced WFM calculations going beyond call center arithmetics, taking fluctuations and flexibility into account.

D

Decimal Separator

The Decimal Separator is the charactar used to indicate where the fractional part of a number begins and where the integer part ends.

The symbol used for the ecimal separator differs per country and is either a dot '.' or a comma ','. Because of this, the decimal separator also differs between versions of excel.

On this website we use the English version of excel, therefore we use the dot as the decimal separator.

E

Erlang

Danish mathematician who created the safety staffing models. Also the dimensionless unit of load.

H

Handling Time

The time spent to handle a service request, which can be calculated over the following PABX metrics: Handling time = Ring time + Talk time + Hold time + Transfer time + Wrap-up time. See also AHT.

I

Intra-Day Management

See RTPM.

L

Load

Amount of work offered to the system, defined by the product of the forecast and the AHT, measured in Erlang. For example: if the forecast of the arrival rate is 4/min and the AHT is 3 minutes, then the load is 4 * 3 = 12 Erlang.

M

Mean

The mean (or average) of a series of numbers of length n is defined as the sum of the numbers in the series divided by n. In formula form this is shown as follows:

\( AV = \frac{1}{n} \sum_{i=1}^{n} a_i = \frac{1}{n}(a_1+a_2+a_3+\cdots+a_n) \)

For example: if our series of numbers is 1 2 3 4 5, then the mean is equal to \( \frac{1}{5} \times (1+2+3+4+5) = \frac{1}{5} \times 15 = 3 \).

The excel function for the mean is AVERAGE()

Metrics

Quantitative measures, commonly used for assessing, comparing, and tracking performance of a system. In contact center, a group of metrics is often displayed in a dashboard for analysis and decision supporting. For example, Handling time, Occupancy, Shrinkage, Longest Idle Agent, etc.

O

Offered Load

See load.

Order of Operations

When we speak about operations mathematically, it means things like add, subtract, multiply, divide, squaring, etc. Remember: If it isn't a number it is probably an operation.

When you see something like ...

7 + (6 × 5² + 3)

... what part should you calculate first?

Start at the left and go to the right?

Or go from right to left?

Warning: Calculate them in the wrong order, and you will get a wrong answer !

So, long ago people agreed to follow rules when doing calculations, and they are:
Do things in Parentheses First. Example:

		6 × (5 + 3)	=	6 × 8	=	48
		6 × (5 + 3)	=	30 + 3	=	33	(wrong)

Exponents (Powers, Roots) before Multiply, Divide, Add or Subtract. Example:

		5 × 2²	=	5 × 4	=	20
		5 × 2²	=	10²	=	100	(wrong)

Multiply or Divide before you Add or Subtract. Example:

		2 + 5 × 3	=	2 + 15	=	17
		2 + 5 × 3	=	7 × 3	=	21	(wrong)

Otherwise just go left to right. Example:

		30 ÷ 5 × 3	=	6 × 3	=	18
		30 ÷ 5 × 3	=	30 ÷ 15	=	2	(wrong)

How Do I Remember It All ... ? PEMDAS !

P	Parentheses first
E	Exponents (ie Powers and Square Roots, etc.)
MD	Multiplication and Division (left-to-right)
AS	Addition and Subtraction (left-to-right)

source: mathisfun.com

P

Poisson

French mathematician (1781-1840) who discovered the Poisson distribution which mathematically describes arrivals to a call center. Also used as Poisson process, focusing on the times of arrivals, and Poisson noise, focusing on the error with respect to the forecast.

Productivity

The time that an agent is available for handling calls divided by the total time that the agent is paid. It can be calculated by; gross workload / gross workforce, or net workforce / gross workforce. Not to be confused with utilization or occupancy.

Q

Quality of Service

See SL.

R

Real-Time Performance Management

See RTPM

S

Seasonality

A forecasting term meaning that a pattern repeats itself, in call centers typically at intra-day, intra-week and intra-year level.

Short Abandon

A call that abandoned very quickly making it unlikely that the caller was already tired of waiting.

U

Utilization

The time that an agent is handling calls (talk time plus wrap-up time) divided by the total time that the agent is paid. It can be calculated by: net workload / gross workforce. Utilization = occupancy * productivity. Not to be confused with productivity or occupancy.

W

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

The amount of available or required agent time when used in capacity calculations. Can be the net or gross workforce. Should match the workload.

Workload

The amount of work on incoming call volume during a certain amount of time, usually measured in minutes. Can be measured without safety staffing (net workload) or with safety staffing (gross workload). Not to be confused with offered load.