Most studies of what causes people to leave their current job (employee turnover) have focused exclusively on full-time employment. Much of this research draws attention to four categories of influence on turnover: work-related factors, such as low job satisfaction; external factors, such as wage-earner status in the household and attractive job alternatives; individual characteristics, such as education and age; and job performance (how well an individual functions in a particular job). A question that arises for industries that rely heavily on part-time labor is whether these factors influence turnover among part-time employees in the same manner that they do among full-time employees. Studies focusing on full-time employment have posited that the higher the employee's educational level, the higher that individual's expectations, leading to greater job dissatisfaction and increased likelihood of turnover. A recent study that focused on turnover among part-time workers suggests that when an individual assumes a part-time job as a secondary activity to supplement household income, it is probable that because of its lower importance, the job will cause considerably less frustration for the individual than will a job that provides a household's primary income. On the other hand, the same study finds support for applying to part-time workers the assertion found in full-time turnover literature that household primary-income earners are less likely than are other workers to leave a job voluntarily.