75. "Consider incentives only as a last resort."

"For most website or post-visit surveys, the best practice is not to provide incentives. Customers want to share their experiences on your website and let you know how you can improve it for them. Incentives usually skew that data because the incentive becomes the motivation, and this usually reduces the quality of the data. It is also harder to detect the pollution in the data. If you don’t have enough respondents, try to optimize the questions, structure, and triggers. Consider incentives only as a last resort."

From “Web Analytics – An Hour a Day” by Avinash Kaushik, Sybex