The upshot is this:
There is strong evidence that employers' use of temporary workers is negatively associated with standard employees' perceived job security, subjective workplace attachment, and relationships with managers and co-workers. These negative relationships are found even after controlling for a large set of organizational, occupational, and individual variables. (p. 35)
While only statistically significant in the model predicting relationships with coworkers, the association between the use of on-call workers and standard employees‘ outcomes is positive across nearly all outcomes. This may mean that on-call workers serve as an institutionalized buffer within workplaces, signaling to standard employees that management is creating organizational slack to protect standard employees from market fluctuations. (pp. 35-36)
These results are important because they confirm the broadly held belief that the presence of a secondary labour force in a workplace can have unexpected and negative outcomes on core employees. But they also suggest that the manner in which an employer employs a peripheral labour force can play a mediating roll—using on-call workers may be a better option than temporary workers.
-- Bob Barnetson