Nübling et al. BMC Public Health 2010, 10:428 http://www.biomedcentral.com/1471-2458/10/428 perspective of the GNH employees are: less emotional demands, better predictability, better quality of leader- ship, and better feedback quality. Differences between HC/GNH and the COPSOQ overall mean Comparisons of the two study groups with the COP- SOQ overall mean (mean value of all participants in all professions, COPall) show significant (p < 0.01) and relevant (delta at least 5 points) differences for the fol- lowing scales (table 2). In the HC again the only negative finding is the lower quantity of social relations. On the other hand, numer- ous positive aspects are found (indicated by a plus sign in table 2): the biggest differences of 10 and more points concern lower quantitative demands, less work-privacy conflict, better predictability, less role conflicts, better quality of leadership, more social support, and a better feedback quality. For the GNH we found fewer significant differences compared to the COPSOQ total. Negative findings were lower influence at work, higher job insecurity, and (as above in comparison to hospital workers) lower self rated general health. Favourable mean values were found primarily in the field of interpersonal relations and leadership, with predictability, quality of leadership and feedback quality showing the biggest differences of at least 10 points. In total, the psychosocial factors at work are favour- able for the HC when compared to each of the other groups: GNH, COPSOQ Hospital Care or COPSOQ overall mean. This is quite obvious for most of the scales in the fields of demands and interpersonal rela- tions and leadership. The only disadvantage for Home Carers is the obligation to work alone most of the time, expressed in the very low value for the scale “social relations”. The situation for GNH is less favourable when com- pared to HC. However, comparing psychosocial factors at work in this group with the external COPSOQ refer- ence values, positive findings prevail especially in the field of interpersonal relations and leadership. Critical findings are the lower values for influence at work and for self rated health and the high value for job insecurity. Subgroup Analysis The relations between the two working schedule aspects frequency of on-call duties and weekly hours worked and the perception of psychological factors, especially focusing on the demands scales, were investigated in a subgroup analysis. This analysis was limited to the employees in the two study groups HC and GNH, respondents working in other occupations (administration) were excluded. Page 7 of 12 Subgroup Analysis: on-call duties In figure 2 the mean values of the four aspects in the field of demands are given for three subgroups formed by the frequency of on-call duties performed in the last month. Most of the 725 study participants in HC and GNH did no on-call duties (N = 510), N = 166 did from 1 to 5 and N = 49 more than 5 on-call duties in the last month. It turns out that the evaluation of job demands in three of the four demand-scales (quantitative demands, emotional demands, and work-privacy conflict) rises sig- nificantly, and more or less linearly (ANOVA, p < 0.01), in proportion to the number of on-call duties performed in the previous month. The differences are particularly clear for the scale work-privacy conflict: here, the mean value for the group with 5 or more on-call shifts is 60 points, compared to 49 points for 1-5 on-call shifts and 42 points for no on-call duty (figure 2). Further significant differences (all with p < 0.01, data not shown) were found for the aspects: influence at work, possibilities for development, role conflicts, and burnout; all these aspects were higher when performing (more) on-call duties. On the other hand job insecurity and quantity of social relations were higher when not performing on-call duties. Across all scales the strongest relations found were for quantity of social relations at work and work-privacy conflict. Subgroup Analysis: hours worked per week 319 persons in HC and GNH work full time (> = 35 hours), 295 part-time with 15-34 hours per week and 106 employees work less than 15 hours per week (5 with no answer). The analysis of job demands according to the number of hours worked per week (figure 3) shows for three of the four scales a significant (ANOVA, p < 0.01) decrease in reported demands as the weekly hours decrease (a positive effect for those working less hours); for demands to hide emotions the level of significance p < 0.01 was not reached. For the aspects quantitative demands, emotional demands, and work-privacy conflict, however, the decrease is not strictly linear in the three groups. Significantly lower demands appear here only for employees with fewer than 15 hours per week (Scheffé-test: p < 0.01 for all comparisons of this group with both of the other groups for the three scales; no significant differences between the two groups with > = 35 h and 15-34 h). Other significant differences according to weekly working hours were found for (p < 0.01, data not shown): influence at work, degrees of freedom, possibili- ties for development (all three in favour for full time workers), role conflicts (higher for full time workers), quality of leadership (higher for part-time employees), quantity of social relations (positive for those working