Hi Mathew
Surveying both grads and employers is important because of their different perspectives. Also you may be required to survey grads, particularly about their employment. To get more candid information from grads you might want to have outside contract workers contact the grads for the information in confidence.
Can you provide more information about your idea to survey random people. What would you be asking them? What would you hope to find out? You might want to survey the business community to determine the kinds of training needed. Or survey individuals to see if they know your school exists. Then plan marketing strategies to reach these people.
Best wishes
Susan