EurWORK European Observatory of Working Life

Impact of work absence on other workers

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A report by the Swedish Institute for Labour Market Policy Evaluation shows that the work absence of colleagues has an important influence on other employees’ behaviour and absence rates. The study examines whether social preferences affect short-term absence and the reasons for this. The results show that social interaction within the workplace plays a significant role in patterns of absenteeism and that a sense of fairness is important for workers.

A new study by the Swedish Institute for Labour Market Policy Evaluation (Institutet för arbetsmarknadspolitisk utvärdering, IFAU) – entitled Sick of your colleague’s absence? (233Kb PDF) – expands further on the findings of a 2008 report (in Swedish, 600Kb PDF), entitled How is the individual affected by sick leave in his/her social network? (SE0809019I).


In 1988, a social experiment was performed in the southwestern city of Gothenburg, Sweden, which investigated the results of easing the sick leave reporting system for half of the population group, known as the case group. The results of the experiment showed an increase in the short-term absence level among these workers, due to their relaxed conditions.

More specifically, the 1988 study was based on data from about 3,000 workplaces within the region around Gothenburg. A randomly assigned group were allowed to be absent from work due to illness for 14 days – rather than the standard rate of seven days – before they needed a doctor’s certificate in order to continue their absence spell with insurance compensation. Participants in the experiment were selected according to their birth date: those with even birth dates were allowed the extended leave system while those with uneven dates maintained the regular leave option and acted as a control group.

The report from 2008 added to the original results by showing that there was a spill-over effect as the control group also increased their level of absence. The authors claimed that this effect was a consequence of social interaction between co-workers. This latest study reinforces that claim.

Aims of study

The aim of the present study is to reveal how co-workers affect each other’s behaviour in the form of work absence. To establish these results, the authors used data from a set of administrative registers compiled by Statistics Sweden (Statistiska Centralbyrån, SCB) during the experiment period in 1988. The latest study posed two major questions as outlined below.

Significance of case group size

In order to determine whether the results of the control group were due to social interaction, whereby colleagues affect each other’s sick leave behaviour, the study investigated the correlation between the change in individual workers’ absence and the proportion of workers in the case group in each workplace. Since the participants in the experiment were selected at an individual level by means of even or uneven birth dates, there was a divergent proportion of workers in the case group and in the control group in each workplace.

The authors hypothesised that, if the proportion of workers in the case group in each workplace correlates with individual work absence decisions, it is proof of co-workers’ ability to affect each others’ behaviour. To find a potential correlation, the authors used a linear regression equation with two depending variables: whether a person is born on an even or uneven date and the number of co-workers in the case group in the workplace.

Reasons for spill-over effects

The second question followed on from the first. Providing that co-workers affect each other, the study sought to identify the reasons for these spill-over effects. The authors established three possible explanations for the spill-over:

  • joint leisure – meaning that co-workers may form bonds and hence enjoy leisure time together;
  • information sharing – meaning that a higher proportion of workers may be correlated with an average absence level simply because more workers – due to the information campaign surrounding the experiment – have become aware of how the system works and thereby increase their level of absence;
  • reciprocity or fairness – meaning that a worker in the control group, observing the extra days off taken by those in the case group, may feel resentment. A natural reaction could be to increase their own absence level, for fairness reasons.

Results of study

The analysis shows that the proportion of workers in the case group in each workplace is highly correlated with an increased level of short-term work absence. The regression analysis finds that an increase in the proportion of colleagues availing of extended sick leave from 0 to 1 increases the change in absence by 0.55 days on average. This result reinforces the authors’ hypothesis that co-workers are able to affect each other’s behaviour through social interaction.

The study then used the same regression equation, albeit with a separation between the case group and control group workers, to distinguish which one of the three explanations above is the most accurate. The analysis reveals that the proportion of case group workers in the workplace had only an insignificant effect on these workers’ absence decisions. However, for the control group, the effect of the proportion of case group workers in the workplace was considerable. If joint leisure was the motivation behind the response to the share of case group workers in the workplace, it would be expected that not only the control group but also other workers in the case group would be affected. Since this was not the case, that explanation is ruled out. The same argument can also be applied for the information sharing explanation.

Hence, the third hypothesis suggesting reciprocity motives appears most likely. The relatively weak effects among other workers in the case group and the strong effect among the control group probably reflects the fairness explanation, where feelings of resentment lead to increased work absence. This explanation more or less rules out the idea of altruistic preferences as a reason for the interaction effects among co-workers.


In summary, the study concludes that social interaction is an important determinant of workers’ effort, as measured by work absence. The authors highlight that, as previous evidence on this issue comes only from laboratory experiments or from studies using observational data from just one company, this study serves as a significant contribution to current literature on spill-over effects at work.

Karolin Lovén, Oxford Research

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