Measuring Levels of Sickness Absence, The Bradford Score, and Using Trigger Points
The management and monitoring of individual or company-wide levels of sickness-absence is greatly facilitated by the use of summary measures. Summaries can be calculated for individual workers, groups of workers (e.g. work departments, age groups, gender) or for the entire workforce.
Sickness-absence summaries can be used for example to:
- Identify the most frequently reported causes of absence
- Describe the levels of sickness-absence across the workforce
- Identify patterns in sickness-absence - by cause, department, calendar period etc
- Identify individual levels of sickness-absence and notify managers when further action may be beneficial ('trigger points')
- Compare sickness-absence levels between departments, staff grades or with other companies of similar size and sector
- Monitor the effect of organisational change.
Two principal aspects of sickness-absence are used - frequency of absence and length of absence.
Frequency of sickness-absence - common measures used include:
- Total number of spells of absence in a specified period
- Average number of spells of absence per employee in a specified period
- Number (or percentage) of employees with any spells of absence in a specified period
Length of sickness-absence - common measures used include:
- Average number of days of sickness absence per absence spell
- Average number of days of sickness absence per employee in a specified period
The Bradford Score is used as a summary measure of sickness absence which combines information on both frequency and length of sickness-absence. The score is calculated as: the number of spells of absence squared, multiplied by the total number of days absent, (i.e. (NumberOfSpells)2 x TotalDays).
- For example, an employee with three spells of absence, of 3, 5 and 2 days over the past twelve months, would have a Bradford Score of (3 x 3) x 10 = 90, for the period.
- Another employee with one spell of 5 days over the same period would obtain a Bradford Score of (1 x 1) x 5 = 5 for the period.
The Bradford Score seeks to indicate the composition of an individual's sickness-absence record, i.e. whether it comprises a few spells of long duration or many spells of short duration and it gives increased weight to higher instances of short term absence, which is viewed by some as being more disruptive.
Trigger points are used in many sickness absence monitoring systems to highlight levels or patterns of sickness absence that require further attention, and to determine where and when action by managers (e.g. employee interview or review of absences) may be beneficial. Typical triggers include:
- Cumulative numbers of days absence in a set period (e.g. absences for more than 10 days in 12 months or for more than 6% of contracted hours)
- Number of spells in a set period (e.g. 3 spells of absence in a 6-month period)
- Bradford Score above a specified limit in a set period (e.g. Bradford Score exceeds 150 in a 12-month period).
- Pattern-related sickness-absence (e.g. a tendency to be off on Fridays or Mondays; sickness absence taken immediately before or after annual or public holidays)
Trigger points can be set in the SART tool to highlight patterns or instances of absence that may warrant further examination. These are described more fully here.