The absence rate, an indicator with no common definition

An absence rate relates days of absence to days theoretically worked. Each of those two terms admits several definitions: calendar or working days, absences of all kinds or sick leave only, with or without maternity leave and workplace accidents.

Those choices, rarely made explicit in publications, produce gaps far exceeding the variations commentary seeks to interpret.

The word itself is a problem. It suggests a conduct, chosen absence, whereas most of the days counted correspond to medically prescribed sick leave. Several statistical agencies therefore prefer to speak of absences for health reasons.

The measured rate depends on the age, sex and occupational composition of the population concerned, since the frequency and duration of absences vary strongly with those dimensions. Occupations exposed to physical strain, for example, show levels out of all proportion to those of office jobs.

Comparing two firms without accounting for their structure therefore amounts to comparing different populations, and the gaps observed partly reflect that composition. Standardisation methods, classic in demography, can correct for this effect, but they are rarely applied to the indicators firms publish.

The same overall rate may result from many short absences or from a few long ones, two situations that call for different readings and do not have the same determinants.

Serious publications therefore systematically distinguish frequency from duration, and analyses of long absences bear more on health than on work organisation. Some management indicators, such as the so-called Bradford factor, weight frequency heavily, a choice that has been criticised because it penalises people with recurring conditions.

Health insurance data supply national series on compensated sick leave, with a stable definition, which allows comparisons over time that company indicators do not.

Those data do not cover uncompensated absences and depend on compensation rules, which have been changed several times, as breaks in series indicate. The three-day waiting period in the private sector, often covered by the employer, makes very short absences partly invisible, for example.

A low rate may reflect good health, a protective organisation, or difficulty in taking leave, the last situation pointing to presenteeism. A high rate is no less ambiguous, since it may reflect difficult conditions as well as an older population.

The indicator alone does not distinguish those three situations, which sharply limits its use as a measure of the quality of working conditions. It only becomes meaningful alongside other information, on staff turnover, workplace accidents or reported conditions.