How to Calculate Schedule Efficiency

An efficient schedule consistently matches the number of rostered agents to the staffing requirement. The forecast workload and shrinkage assumptions determine this requirement.

Improving schedule efficiency helps minimise periods of over-staffing and under-staffing.

The planner’s ability to perfectly match staffing with requirements is constrained by the limitations that he or she inherits:

Where there are few or no part-time staff, rigid scheduling rules can make shift planning difficult. Fixed start and finish times, consecutive days off and set break windows can make it harder to match shifts to peaks and troughs in demand.

Nevertheless, a good WFM team will apply creativity in finding and leveraging whatever flexibility exists. For example, even if start and finish times cannot be varied, optimum placement of breaks and meetings can work wonders for schedule efficiency.

Keeping the mismatch between ‘supply and demand’ as low as possible helps ensure better use of personnel. It also supports consistent service levels, occupancy levels and lower costs.

Knowing where mismatches occur helps the WFM team build better schedules within the rules in place. It also encourages the wider operation to identify new shift types and hiring options.

If the forecast is reasonably accurate and schedules match it well, the intraday chaos of constant adjustments can be minimised.

For some ideas on improving your contact centre schedules, have a read of this article on Workforce Optimisation: 10 Ways to Improve Your Contact Centre Schedules.

How to Calculate Schedule Efficiency

Here is a five step approach to calculating schedule efficiency in the contact centre.

Step 1 – Shrinkage Adjustment

You must choose the shrinkage adjustment wisely. Bear in mind that shrinkage may or may not be a constant. It might vary over time.

For example, shrinkage is often higher during the summer holiday season. It can also vary by day and week. And make sure you use the correct calculation formula.

If the shrinkage percentage is s%, you should inflate the number of scheduled staff by dividing by (1-s%), not multiplying by (1+s%).

Example: If 70 employees must be on duty to meet the Service Level goal and shrinkage is 30%, you should schedule 100 people. The calculation is 70 / (1 – 0.3) = 100. Adding 30% to 70 would only give you 91.

The shrinkage percentage assumption can be added in each interval to raise the bodies in chairs requirement to the number that is actually needed on the schedule so that absenteeism and other factors can occur without impacting the service delivery.

Step 2 – Total Required ‘Bums in Seats’

This is based on the forecast – see section 1 above – inflated by the shrinkage adjustment. Where a skill-based routing configuration is in place, a sophisticated algorithm is needed to take into account the pooling efficiencies offered by multi-skilled agents when calculating required staffing.

In a traditional single-skilled environment, basic Erlang C will be acceptable for inbound calls – but bear in mind that other channels such as webchat, email and social media will need a different approach.

Step 3 – Total Scheduled Staff in Each Period

This is the staff scheduled, including the shrinkage assumption not yet covered by the schedule elements. For example, next week’s schedules may already include planned vacations and training. However, daily absenteeism would still need to be included as a shrinkage assumption.

In a single-skilled environment this will be relatively easy to determine, but it is more complex in skill-based configurations where a single agent may be capable of serving more than one type of call at any moment in time.

(If preferred, the shrinkage can be deducted from the scheduled staff rather than added to the ‘bums on seats’ calculation).

Step 4 – Total Variation of Scheduled Staff Compared to Required Staff

This is a measure of mismatch between ‘supply and demand’ across a period. When the ‘overs’ and ‘unders’ are added together, the total for the period is divided by the total requirements for that period.

The result is the percent of variation staffing v. requirements. (A standard deviation analysis of the variances can be done if the over- and under-staffing numbers are converted to percentages of variation by period.

When the staffing requirements by period vary significantly by day or week or time of day, the raw numbers of staff variance will provide an inaccurate result).

Step 5 – Analysis Period

This should generally be analysed at the day or week level, although analysis of the patterns of intraday variations can be effective in determining trends of mismatch.

Written by: Chris Dealy

For more on the topic of calculating key metrics for contact centre WFM, read our articles:

• How to Calculate Forecast Accuracy
• How to Calculate Contact Centre Service Level
• How do I Calculate… Schedule Adherence

Reviewed by: Hannah Swankie