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:
• The sampling approach works best for populations over 1,000 individuals • This approach avoids fatiguing respondents • Segmentation allows you to obtain information on particular subgroups If you are going to take the sampling approach, be mindful of the number of responses required to get a solid indication of how the target population overall would respond to your questions.
To ensure good sampling, make sure your selection of population is as random as possible. Send scheduled email reminders. Do not invite all potential respondents, thereby leaving names available for future surveys. For web surveys, make sure they are representative of the population for which you have email addresses; you may need to expand and test the representativeness and comprehensiveness of your house email lists.