The HRM director of a manufacturing company wants to offer stress management seminars to personnel who experience high levels of job-related stress. Before offering the seminars, she needs to be sure that there will be a demand for them, and proposes to survey a sample of employees in these roles. She believes that three groups are most likely to suffer job-related stress: those employees who constantly handle dangerous chemicals, the production supervisors, and the middle managers. Design a sampling process which would be appropriate for the HRM director to use.