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Operational Research

You can always be more efficient

Operational Research is all about using analysis to improve decision making. Dr Angela Moore uses mathematical modeling, statistical analysis, optimisation, sequencing and scheduling techniques to create simple heuristics you can employ to run your operation more efficiently.

Match Your Workload

When creating a shift schedule you need somewhere to start. A good place is to look at the times you want to cover. So we start off the process by creating an ‘Hours Table’. It’s simple, along the top are the 24 hours of the day and down the side are the seven days of the week.

 hours table

This figure is an example of the ‘Hours Table’. In this example the operation requires three people on during core hours Monday-Saturday 8am-4pm. During the rest of the week they require two people at all times. At the end of the table is a count of the total number of hours for each day and the week. In this example these staffing levels would require 384 hours per week.

Such a simple tool, yet from it you can work out the hours you require per week, and hence the number of people you need to employ to operate efficiently.

Every time we have an enquiry, we send them an Hours Table to fill out. You can download your own copy from On the Excel file there are two ‘Hours Tables’. One for their ideal staffing levels, and one on the minimum staffing levels. This is a great way to focus you, so you can consider what you can cope with and what you would like if you had unlimited resources.

We then take these two tables and work out how many people you require for both workloads. Our e-book for calculating how many staff you require, is available from amazon.

So now we know how many people you want on at all times and how many staff you require for each option.

Now no one has unlimited resources, and unless this is a ‘green field’ operation you already employ a number of staff for this operation. So we compare the number you have with the two workloads. Most of the time companies employ a number closer to the minimum staffing levels.

On occasion we have found that they have more staff then the ideal scenario, this is normally why they have called us in.

  • One reason why this happens is when the company has just upgraded their equipment. The new equipment requires fewer operators but in order to justify the cost of the equipment it has to be run continuously. They don’t want the operation disrupted by holidays and absences.
  • Another reason for over staffing, could be that departments or groups have been amalgamated. This often leads to economies of scale.
  • There can also be a change in the workload, which can lead to a change in requirement. This can happen as the result of a natural change or if a contract has just finished.
  • Sometimes procedural changes can affect the required number of staff, such as using agency staff to cover for absences instead of internally.
  • At other times we are called in after a takeover or buy out. The new company want to introduce efficiency changes and the old way of working is surpassed by moving to a more efficient approach.
  • Another decision that effects the staffing numbers quite dramatically is the move from flat staffing to variable staffing. If we take the example above where they require three on only during core hours and two at all other times. What if before they had three on at all times? The move would reduce the staffing requirement by nearly 24%.

Creating the Shifts

Once we have matched the current staffing levels to the staffing profile, the next stage is to create the shifts. This is very much an art form. You need to balance the length of the shifts, with their respective start and finish times. This can be a delicate balance. The type of work and the breaks will play a crucial role is deciding what shifts you will use.

So we have developed an Excel spreadsheet that allows us to create the shifts and plots them against the desired staffing profile for each day. So with the example where three are required on during core hours and two at all other times, let’s see what shifts would support this profile best. The graph below shows how we match the required staffing numbers to the number supplied by the shifts. Each day would have a different staffing requirement we would have to match. The one below would work for Monday to Saturday in this example. The required number would be entered from the ‘Hours Table’. The Shift Number would be based on the shifts we created. This way we can check if the shifts met the requirement. In this example we have matched the requirement.staffing graph


When creating the shifts we need to think about the type of work these shifts will be covering. What are breaks like? Are they paid or unpaid. Then are they taken as and when the work allows or do they need a cover person on to cover for breaks? For this example let’s make it simple; the breaks will be paid and taken as and when the workload allows.

OK but how long can they work for? A shift should be long enough that they will come into work, but not too long that it makes them fatigued. If you are doing original mental work e.g. learning a new skill, creating a new product or process, you need short days. From a mental fatigue point of view you need to limit your employees to about 5 hours. After 5 hours their mental processes start to slow down and they make mistakes or can't retain information as well. Therefore any work they do after the 5 hours just has to be repeated the following day. Which eats into the five hours of the following day and creates a vicious circle.

For most operations the shift lengths will be either 8 or 12 hours on average. 8-hours are popular for five day working and work that is physically or mentally demanding. If the work allows for 12-hours, than 12-hour shifts are always more popular. Sometimes companies opt for a mixture, an option we would always put forward unless there are fatigue reasons why this would not be appropriate. You could even go with a maximum of 10-hours, or any other shift length you liked. The reason for advising longer shift lengths unless fatigue is an issue, is that it limits the number of commutes and maximise their time off. When introducing change it is a good idea to make the new operation more attractive to the shift workers than the old.

So let’s assume that the shift lengths have to be longer than 6-hours to make it desirable to come into work, but the work is not physically or mentally demanding so we can set the maximum to 12-hours.

So what shifts can we use to cover the workload? There is the obvious option, we use 12-hour shifts to cover the background workload. So we have four 12-hour shifts each day. Two day shifts and two night shifts. This would give us two people on at all times. Then we use an 8-hour day shift to give us one extra person on Monday-Saturday during core hours. Easy!

Shifts Table

So then there is the question of start and finish times. You could have all of the day shifts starting at 8am. Or you can stagger the start times so that you don’t need handovers. Most jobs will take more than a few minutes to do, so allowing a handover so that people can transfer jobs as they come in depending on when their shift finishes makes a more efficient process. So we start the 8-hour shift at 8am. Then we can set one of the 12-hour shifts to be 8am-8pm and 8pm-8am. The other could be set 7am-7pm. This gives a one hour handover during shift changes.

If you wanted to avoid using 12-hour shifts, the work could be done using just 8-hour shifts or a combination of 8 and 10-hour shifts.

Once we have selected the shifts, then we create a shifts table. The shifts table names each of the shifts, gives its start and finish times plus the paid length of the shift. This table can then be compared to the ‘Hours Table’ to ensure that all of the desired hours are covered by these shifts.shift table 1

The figure above shows the shifts table using 12 and 8 hour shifts. Then you need to create a shift requirement table. This just tells you how many of each shift you require each day of the week.

shift table 2

The shift requirement table above shows you how many of each shift you require each day. So you would require one of each of the 12-hour shifts each day. However you only need one of the shorter 8-hour shifts on Monday to Saturday. So you would need 34 shifts per week. If you were operating with a 40 hour week, you would require about 12 people to cover the workload, holidays and absences. So everyone would work an average of about 3 shifts per week plus cover shifts for holidays and absence cover.

Using 10 & 8-hour Shifts

If you chose to use a combination of 8 and 10-hour shifts then the tables would look slightly different.

shift table 3

The figure above shows the shifts table using 10 and 8 hour shifts. This time there are six different shifts. The start and finish times in this example could be changed if they are at inappropriate times. You need to balance the start and finish times of a shift. If the shift starts too early it can cause people problems with their sleep and commuting. If it finishes too late then it can cause problems with people getting to sleep when they get home. Few shifts start between midnight and 6am.

Once you have a shifts table then you need to create a shift requirement table. Here is the shift requirements table for the 10 and 8-hour option.shift table 4

The shift requirement table above shows you how many of each shift you require each day. So you would require one of each of the shifts Monday to Saturday. However on Sunday you only need the Early, Morning, Afternoon, Late and Night shift. So you would need 41 shifts per week. If you were operating with a 40 hour week, you would require about 12 people to cover the workload, holidays and absences. So everyone would work an average of about 3.5 shifts per week plus cover shifts for holidays and absence cover.

By bringing the maximum length of shift down from 12 to 10 hours, everyone would have to work about 26 more shifts per year. If on average everyone commutes for an hour each way, which would mean an extra 52 hours commuting each year. This is why 12-hour shifts are more popular. Then there is more shifts at weekends to consider. On the 12 and 8-hour shifts, there were 9 shifts at weekends. Now assuming that you used a pattern that didn’t have split weekends, on average each person would have to work about 22 weekends per year. On the 8 and 10 hour shift pattern, they would have to work about 26 weekends per year on average. That is four extra weekends each per year.


Shifts and Hours tables are the corner stone of shift scheduling. If you don’t know what staffing levels you are trying to match then you will always be incorrectly staffed. Saving just one hour per day is the equivalent of saving one fifth of a person per year. So identifying those hours when you can cope with one person less, soon adds up to real savings.

If you would like some help creating a shift schedule then please contact us directly. You can download your own copy of the ‘Hours Forms’ from This Excel file is for one hour increments, however we also do them in half hour and quarter hour increments too depending upon your workload requirement. Academic organisations often have two sets of Hours Tables, one for Term and one for Vacation Weeks.