Journal of Occupational Health Psychology Copyright 2000 by the Educational Publishing Foundation 2000, Vol. 5, No. I, 182-190 1076-8998/00/$5.00 DOI: 10.1037//1076-8998.5.1.182 A Multilevel Analysis of the Demands--Control Model: Is Stress at Work Determined by Factors at the Group Level or the Individual Level? Nico W. Van Yperen and Tom A. B. Snijders University of Groningen This study explored the extent to which negative health-related outcomes are associated with differences between work groups and with differences between individuals within work groups using R. A. Karasek's (1979) demands-control model. The sample consisted of 260 employees in 31 working groups of a national bank in the Netherlands. Results suggest that job demands and job control should be conceptualized as having both group- and individual-level foundations. Support for Karasek's demands--control model was found only when these variables were split into the 2 parts, reflecting shared perceptions and employees' subjective assessment, respectively. One of the most appealing practical implications is that absence rates among homogeneous work groups can be reduced by enhancing actual control on the job. Despite the importance of the organizational sciences, very little is known about the extent to which organizational behavior and work-related well-being can be explained by environmental factors and by employees' subjective assessment. This distinction is important because of its theoretical and practical implications. For example, from an environ- mental perspective, work-related well-being and health outcomes can be enhanced by redesigning jobs with the aim of increasing actual control on the job (cf. Karasek & Theorell, 1990; Landsbergis, 1988). On the other hand, others (e.g., Bandura, 1986; Lazarus & Folkman, 1984) have explained well-being in terms of a particular relationship between the person and the environment, emphasizing that well-being can be enhanced by analysis and treatment of the environment, the individual, or both. A model that explains psychological well-being and physical illness primarily in terms of environmen- tal factors is Karasek's (1979) demands--control model (or decision latitude model). The central contention of this well-known model is that it is not Nico W. Van Yperen, Department of Social and Organiza- tional Psychology, University of Groningen, Groningen, the Netherlands; Tom A. B. Snijders, Department of Statistics and Measurement Theory, University of Groningen, Gro- ningen, the Netherlands. We are grateful to Jolly Postma for her help in data collection. We also thank MariEt Hagedoorn and Theo Meijman for their helpful comments on a draft of this article. Correspondence concerning this article should be ad- dressed to Nico W. Van Yperen, University of Groningen, Department of Social and Organizational Psychology, Grote Kruisstraat 2/1, 9712 TS Groningen, the Netherlands. Electronic mail may be sent to n.van.yperen@ppsw.rug.nl. high demands per se, but high demands in combina- tion with a lack of control on the job that are associated with negative health-related outcomes. Although evidence has been found for relationships between job demands and control on the job, on the one hand, and mental health and illness, on the other, support for the proposed interaction between both variables is not strong (e.g., Dollard & Winefield, 1998; Ganster & Fusilier, 1989; Landsbergis, Schnail, Schwartz, Warren, & Picketing, 1995; Parkes, 1991; Parkes, Mendham, & Von Rabenau, 1994; Schaubroeck & Merritt, 1997; Theoreli & Karasek, 1996; Wall, Jackson, Mullarkey, & Parker, 1996). Wall et al. (1996) explained the weak support by the lack of correspondence between the theoretical construct of control and the way this construct is generally measured. They argued that control is the critical variable that should not be assessed by measures encompassing a wide range of job proper- ties (such as Karasek's job decision latitude). Indeed, Wail et al. found clear support for the interactive demands-control model using a more focused mea- sure of job control. In contrast, with a variable that is equivalent in content to earlier-used measures of decision latitude, no interaction effect was observed. A question that remains, however, is whether job control operates at the individual level, the group level, or both. Thus, an additional explanation for the inconsistent findings of tests of the demand--control model may be the confusion between the distinct conceptual levels: the individual and the work group. An essential aspect of data on organizational settings is the hierarchical structure, namely, employees are nested within work 182