In order to increase employee satisfaction around their schedule, some industries have created constraints to ensure fairness and rotations of difficult shifts (typically night and weekend shifts).
For example, a constraint to distribute night shifts fairly to all employees would need to be defined on both the how and the span (see horizon constraints). Lets say you count shifts that are from 11pm to 7am over a 3-week period. Is that enough to be fair? Employees who will be on vacation will work less night shifts during that time span and therefore will work less night shifts.
The fairness aspect of any counter relies more on its perception than on the real value. I have seen planners count on an endless horizon and employees had the number of hours worked in their entire employment time with some employees with well over 15,000 hours in that counter. A new employee comes in at 0…
Fairness is not only about what employees don’t want, but also about what employees want. Instead of counting night shifts, you could count day shifts since that is what everyone wants. You could count both and make sure everyone get their fair share.
So what is a fair share? First, you need to make sure that the share is counted properly between employees. A part-time employee should not work the same amount of night shifts as a full-time employee, but should work the same relative number of night shifts than a full-time employee. A fair share can be counted in percentage (night shift count divided by all shift count). If you exclude absences from the total shift count, then you have a value you can share with all.
Now some will get to be picky, and say they worked 25% night shifts this period and buddy here just worked 22%, so next period that employee should be lower. What you can establish as a fairness of distribution is to plan against a rolling average of percentages using the last 10 periods for example. This way, an employee who worked more night shifts than others would have to work less the following periods in order to reduce the rolling average and keep everyone at the same level.
If you need to equalize what employees are trying to have, one methodology is to keep a rolling counter. Usually, employees fight for things that give more money like overtime. If you need to equalize overtime, you need to offer the same fair chance of overtime to everyone. Since overtime is not always planned for, a planner needs to keep counters on who should be called next. One of the simplest ways to keep track of who is next on overtime is to keep a rotating list of calls. You establish the list of employees in a certain order and keep moving on to the next employee to offer overtime shifts. Notice that I used the verb ’offer’ instead of ‘assign’. This is because employees will refuse overtime for all sorts of reasons and although they refuse, they would always be at the top of the list. This causes the planner to call that employee all the time even though the planner knows for sure to get a refusal. By counting what’s offered (overtime accepted or not), the number of calls for the planner is reduced while keeping the staff with a higher sense of justice.
This rotating list can be counted in occurrences, but in some industries the overtime offered will never be of the same duration. In these cases, a planner should count the hours that were offered. The next employee to call is therefore the one with the least amount of overtime hours offered. Just like any other counter, this one also needs to be on a certain horizon. It can either be reset at 0 at the beginning of each year or be on a rolling horizon of the past 10 months for example.
Whatever you decide on what your fairness counters should be, you also need to define the rules that dictate how to count and what to do in rare cases. For example, where do you insert a new employee in the overtime list with what value? That new employee has 0 hours and would always be called until enough hours are offered for that person to catch up to the others. Now that would not be fair. Most businesses pre-assign this new employee with the highest value on the list (so they would be last as of their first day of work) or assign the average value of all employees.
Either case, the point is that some guidelines are required around the interpretation of fairness counters.