There are four main ways of measuring time lost to sickness absence in the workplace. These are:
- Lost time rate;
- Frequency rate;
- Individual frequency rate; and
- Bradford factor.
In this article, we provide an overview of each of these methods and explain sickness absence rate calculations using these approaches.
Let’s dive straight in and learn about measuring absence in the workplace.
Why we need to be measuring absence
According to research, the sickness absence rate has jumped to the highest it’s been for a decade.
This surge shows just how important it is for organisations to measure and understand workplace absences. But let’s take a look at why…
Firstly, absences directly impact productivity. When employees are frequently absent, workloads shift, causing stress and pressure amongst others in the team. This ripple effect can lead to burnout, disengaged employees, and even more absences—a cycle that’s tough to break.
Tracking absences can help us gain an insight into the wellbeing of our workforce. Are people getting sick often, or is there an underlying issue like stress or burnout? Understanding why employees are missing work can help you offer the right support, from flexible hours to EAP services, leading to (you guessed it) a healthier workforce with lower absences.
Absence measurement also keeps costs in check. Absenteeism can drain resources quickly, with lost productivity and the need for temporary cover adding up. Having a clear view of attendance trends means that people managers can staff effectively, reducing the financial burden of unplanned absences.
Lost time absence rate
The most commonly used measure is the lost time rate which shows the percentage of total time available that has been lost due to any type of absence during a certain time period. To calculate the lost time rate, divide the total absence in hours or days in the chosen period by the possible total in hours or days in that period, then multiply by 100.
For instance, take a total absence of 120 hours in a possible 1500 total hours available in that period, the lost time rate is: 120/1500 x 100 = 8% (rounded to the nearest 0.5%)
The lost time rate is useful as a general measure of the gravity of sickness absence levels for an organisation. Teams or departments who want to ascertain whether or not there are absence issues in certain areas can also use this measure. But, as this measure gives only an overview of the time lost, a small number of employees who are on long-term sickness absence or a larger number of employees who have a high number of short-term sickness absences can distort the figures. To see the extent of the problem, a better measure to use would be the frequency rate.
Frequency absence rate
The frequency rate calculates the average number of periods of absence per employee as a percentage. It gives no indication of the length of each sickness absence period and no indication of employees who have taken more than one period of absence. It is calculated by dividing the number of spells of absence in the period by the number of employees in the period, and then multiplying by 100.
So if you employed an average of 75 staff members in a three-month period, and had a total of 19 periods of sickness absence in that time, the frequency rate for absence would be: 19/75 x 100 = 25.5% (rounded to the nearest 0.5%)
Individual frequency absence rate
To show as a percentage the number of individual employees who have been absent during a period of time, you will need to use the individual frequency rate. Like the frequency rate, it doesn’t show the length of each sickness absence period. To calculate the individual frequency rate, divide the number of employees taking one or more spells of absence during a period by the number of employees in the period, then multiply by 100.
To illustrate this measure using the frequency rate example above, if the 19 periods of absence in a three-month period consisted of the absence of 11 employees, one who was absent four times, one who was absent three times, two who were absent twice and 7 who were absent once, the individual frequency rate would be: 11/75 x 100 = 14.5% (rounded to the nearest 0.5%)
Bradford factor
To identify the organisational disturbance caused by persistent short-term absence for individual employees, the Bradford factor should be employed. This method gives extra weight to the number of periods of sickness absence taken per employee. The Bradford score is S x S x D – S being the number of spells of absence in 52 weeks taken by an employee and D the number of days of absence in 52 weeks taken by that employee.
A working example would be, if an employee has four spells of absence that total nine days of absence in 52 weeks, the Bradford factor would be: 4 x 4 x 9 = 144
For organisations setting absence triggers to investigate absence when it reaches a certain trigger level, the Bradford factor can be a useful measure of sickness absence.
For more information on setting absence triggers to help manage sickness absence in your organisation, you may find the following article useful:
How to use action and metric figures to manage absence
Measuring absence – how we can help.
If you’d like HR support with an absence management query, please do contact us on 0330 223 5253.
