When is it necessary?

Reproduced from Appendix 1 to the ACAS Guide Managing Attendance and Employee Turnover

Measuring absence

The most common measure of absence is the lost time rate. This shows the percentage of the total time available which has been lost because of absence from all causes in a given period.

Total absence (hours or days)
in the period
x 100 = Lost time rate
Possible total (hours or days)
available in the period

For example, if the total absence in the period is 124 hours, and the possible total is 1,550 hours, the lost time rate is:

124 x 100 = 8%

The lost time rate can be regarded as an overall measure of the severity of the problem. If calculated separately by department or group of workers, it can show up particular problem areas.

Total time lost, however, may consist of a small number of people who are absent for long periods, or a large number absent for short spells. A measure of ‘frequency’ is needed to show how widespread the problem is, so that companies can formulate appropriate plans to reduce it.

The frequency rate shows the average number of spells of absence per worker (expressed as a percentage) irrespective of the length of each spell.

Number of spells of absence in the period x 100 = Frequency rate
Number of workers in the period

If the organisation wishes to monitor the number of workers absent at all during the period the individual frequency rate can be used:

Number of workers having one
or more spells of absence
x 100 = Individual frequency rate
Number of workers

For example, in one month an organisation employed on average, 80 workers. During this time 12 workers had periods of absence: one was away three times, two were away twice and nine were away once, a total number of 16 spells of absence. The frequency rate was therefore:

16 x 100 = 20%

The individual frequency rate was:

12 x 100 = 15%

Another individual index of absence, developed by Bradford University, highlights repeated short-term absence by giving extra weight to the number of absences. It is given by the formula:

8Index (I) = S x S x H, where:
S = the number of absences; and
H = total hours absent in any given period

For example:
Worker with two periods of absence totalling 10 days (80 hours):
I = 2 x 2 x 80 = 320

Absentee with six periods of absence totalling 10 days (80 hours):
I = 6 x 6 x 80 = 2880

Organisations can use the indicator to provide a trigger point for investigation. It is important, however, to examine the particular circumstances leading to a high score before action is taken.