“…The two groups may also have different types of work and family circumstances. A series of studies in the United States found employees had different occupations (Masuo, Walker, & Furry, 1992), made more contribution to family income, had one rather than two jobs (Loker & Scannell, 1992), had family present more often (Rowe & Bentley, 1992), and experienced less variation in work flow (Heck, Saltford, Rowe, & Owen, 1992). It is therefore preferable to study employees separately.…”