In 7 Habits of Highly Successful Surveys, marketing experts at Vovic Corporation write on surveying the right number of people:
Some might consider a “census approach” to surveying, attempting to gather feedback from 100% of the population. Others take a “sampling approach”. If you are thinking of taking a census approach with your survey, consider:
• The census approach works best for populations under 1,000 individuals • It may require you to utilize incentives to boost response to the appropriate level • Make sure you invite all respondents • Use reminders and deadlines to ensure highest response rates among your population A sampling approach may be more effective for your situation. Some of the benefits of a sampling approach are as follows: