Here are few tips:
- First and foremost, write a survey plan before launching a customer survey!
- Watch male/female bias in questions
- Balance male/female response rates
- Be sure to specify customer segment criteria. For example, in a retail environment: Participant spends more than $X per year
- Watch response rates if multiple segments are being surveyed at once to ensure statistical validity
- Put customers in zip code array and pick every nth name to ensure geographic coverage
- Determine how many customers you will need to sample (2 times, 5 times, or 10 times the number of completed surveys) to get the desired number of returns.
- Be sure to pilot all new surveys prior to full implementation. For example, in one survey a company asked, "Describe the customer service traits of a company that you admire." Many customers answered this question as if the "admired company" was the company sending the survey. Needless to say, these answers would definitely skew the data.