Response rates can be improved by o

Response rates can be improved by offering respondents an incentive for
completing the survey, such as a chance at winning a grand prize, a lower
priced incentive for every respondent, or even the knowledge that they are
improving a product or service that they care about.
There is a train of thought that paying incentives is not always a good thing.
Amongst less affluent or educated respondents it may predispose them to feel
that they need to give so-called “good” or “correct” answers which may bias
your results. Alternatively you may attract respondents who are in it just for
the reward. One approach could be to run the survey with no incentive with the
option to offer one if responses are limited.