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An excellent roster is one that best meets and enables a unit’s staffing coverage requirements. Real life is complex and nuanced, so simple representations of which staff we need and when we need them can always be improved. In this article, we present four different levels of staffing optimisation. Each level represents a more complex rostering problem, allowing for more optimisation possibilities and considerably more effort and skill to construct.

Why Optimise?

The consequences of neglecting critical staffing factors when creating a roster, can range from tears and distress to dangerous gaps in the workforce capabilities needed for the challenges of the day. Obviously, at the basic level you need to have the right number of staff working each day. However, there's so much more that can be delivered in a complex roster that can positively impact staff satisfaction, productivity, safety and customer satisfaction.

Level 1: Day Assignment

The most basic coverage level to consider is having the correct number of people on hand each day. It can be tempting to think that getting your staffing right is a simple calculation based on having the right number of FTE available to you to cover your roster, and it would be if one could freely allocate shifts to each employee. In actuality, it can be hard to freely move people around for many organisations due to the constraints of individual staff members. People will have different availabilities on different days and may have contractually guaranteed work hours. You might also have the complication of guaranteed roster patterns, such as fixed days on into days off style rotating schedules. Even with these constraints, there is usually some wriggle room to change the days each person is allocated to work in a roster to optimise for better coverage.

Level 2: Day-Shift Assignment

A day can have the right number of people working but still have an overstaffed morning shift and an understaffed afternoon shift. Getting a good balance of staff working each shift can be difficult due to minimum hours between shifts, fairness around shift distribution, and contractual shift assignments. Sometimes shifts can be moved around to cover different peaks and troughs of business, especially when there is 24-hour coverage and multiple different shift lengths within each day. Having the right number on hand for each time period or shift is essential.

Level 3: Day-Shift-Task Assignment

When we traditionally think of shifts, a lot of information is encoded in a very simple shorthand. The fundamentals are always there; when the shift is expected to start and end. Implicitly there is an associated location for the shift, usually as there is only one place of work for the shift to occur, but this is not always the case. Beyond just time and location, we can also assign a specific role to a staff member during the shift, e.g., designated team leader for the shift or a required specialist. As multiple shifts can have the same location or role, we usually represent these components of the shift as a "task".

Optimising task coverage must be considered simultaneously with which employees work which shifts on which days. If you take a schedule which was made while only considering day and shift coverage, you will often find that many shifts lack employees who can perform certain tasks and it is impossible to cover all those tasks. It will take so many shift changes to make the original roster work that you may as well make the roster from scratch. This same difficulty also applies to our next level of optimisation, in skills mix.

Level 4: Day-Shift-Task Assignment with Skills Mix

Separate from tasks is having the right skills available on every shift. The distinction between tasks and skills might be a little murky since they are both ways of checking that every shift has the correct people on. The way I think about it is that tasks are what people do during a shift, whereas skills are attached to the person. Skills can be formal, such as a certificate or license, the competency to use a specific machine, or informal, such as being a more senior team member. When writing a roster, we must acknowledge that there is a need to ensure each shift is adequately skilled, lest we create a time when only junior staff work. A roster that optimises for effort, skills, employment constraints and staff preferences will deliver the most benefit in terms of productivity, safety, legal compliance and staff satisfaction. Well worth the effort!


We've peeled back the layers of complexity that exist for optimising a roster. Each optimisation level requires an increasing amount of time, effort, and resources. This is because the rosterer must consider not only the number of people needed but also the tasks and skills required for each shift. The additional effort and resources needed for higher levels of optimisation may include managing data on employee availability, skills, and contracts. A software tool such as Rosterlab AI can store all relevant data and automatically create rosters considering all four levels of staffing optimisation.

Staff rostering optimisationStaff scheduling optimisationRota optimisation