Measuring Time Lost

There are a number of measures that can be used to assess absence, each of which gives information about different aspects of absence.

‘Lost time’ rate

This measure expresses the percentage of total time available which has been lost due to absence:

Total absence (hours or days) in the period x 100

Possible total (hours or days) in the period

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

124     x 100 = 8 %

1,550

It can be calculated separately for individual departments of groups of employees to reveal particular absence problems.

Frequency rate

The method shows the average number of absences per employee, expressed as a percentage. It does not give any indication of the length of each absence period, nor any indication of employees who take more than one spell of absence:

No of spells of absence in the period x 100

No of employees

For example, if in one month and organisation employed on average 80 workers, and during this time there were a total of 16 spells of absence, the frequency rate is:

16 x 100 = 20%

80

By counting the number of employees who take at least one spell of absence in the period, rather than to total number of spells of absence, this calculation gives an individual frequency rate.

Bradford Factor

The Bradford Factor identifies persistent short-term absence for individuals, by measuring the number of spells of absence, and is therefore a useful measure of the disruption caused by this type of absence. It is calculated using the formula:

S x S x D S = number of spells of absence in 52 weeks taken by an individual

D = number of days of absence in 52 weeks taken by that individual

For example:

10 one-day absences: 10 x 10 x 10 = 1,000

1 ten-day absence: 1 x 1 x 10 = 10

5 two-day absences: 5 x 5 x 10 = 250

2 five-day absences: 2 x 2 x 10 = 40

The trigger points will differ between organisations. As for all unauthorised absence, the underlying causes will need to be identified.