Population estimates have been and are routinely used by the Illinois Department of Public Health as denominators in various rate calculations.  Birth and death rates are prime examples.  Population estimates are also used to determine target populations.  For example, the Illinois Department of Public Health’s Facilities Development Division has a certificate-of-need process that uses population estimates in assessing bed needs in hospital planning areas.  Population estimates are also used as controls in producing more detailed population estimates, such as by age and sex.  In addition, grant applications for proposed health-related projects often require population figures.  Accurate population estimates are also vital to the work of other health and social service agencies, both public and private.