2.2.1. Stress

Lazarus and Folkman defined stress as "a relationship with the environment that the person appraises as significant for his or her wellbeing and in which the demands tax or exceed available coping resources" [20]. Stress was measured using the Perceived Stress Scale (PSS) about events in the last month using the following items: upset because of something that happened unexpectedly; unable to control the important things in your life; nervous and "stressed"; confident about your ability to handle your personal problems; things were going your way; you could not cope with all the things that you had to do; you have been able to control irritations in your life; you were on top of things; angered because of things that were outside of your control; and difficulties were piling up so high that you could not overcome them. This scale has been used significantly in measuring the stress estimates with strong psychometric properties [31]. Cohen et al. argue that PSS is highly correlated with various scales, making it have good validity. These may include health behavior measures, smoking status, help-seeking behavior, self-reported health, and health services measures. The participants assessed the intensity to which life stressors were overwhelming and unmanageable over the previous month. They used a scale ranging from 0 (never) to 4 (very often), with a higher score referring to a higher stress level. The scale in the original study has good reliability and validity (Cronbach's alpha 0.85).

#### 2.2.2. Work Role Conflict

Role conflict is "the extent to which one experiences incompatible work demands" [32]. This study uses the role conflict measure for workers developed by Bowling et al. to evaluate the work-role conflict among primary healthcare workers [32]. The measure has six items and provided answers ranging from 1 (strongly disagree) to 7 (strongly agree), with a higher score on the scale pointing to a higher conflict level. The scale includes the

following items: in my job, I often feel like different people are "pulling me in different directions"; I have to deal with competing demands at work; my superiors often tell me to do two different things that cannot both be done; the tasks I am assigned at work rarely come into conflict with each other; the things I am told to do at work do not conflict with each other, in my job; and I am seldom placed in a situation where one job duty conflicts with other job duties. In the original study, the scale has a reliability (Chronbach's Alpha = 0.62) which is acceptable reliability [33], as well as criterion validity with the Perceived Stress Scale (r = 0.472, *p* < 0.01).
