Hello, David -

I recently hired SurveyMonkey.com to disseminate my survey (for my dissertation) to its audience. While you can disseminate your surveys yourself, I needed a fast response to my two questionnaires. That company offers points to qualifying participants who meet the inclusion criteria specified by the researcher. These points may be donated to a charity of the participant's choice and SurveyMonkey converts them into a cash amount when paying the charity. This encourages participants to complete surveys. This has been my only experience with formal surveying thus far. Some of my peers who have conducted qualitative research have offered free pizza (at focus group gatherings), and gift cards. My experience hiring a company that offers incentives was extremely positive - however, it was expensive ($1800 for 300 responses).

Depending on your sample size, you can do different things. It also depends on the topic. I was once working on effect or workshops on undergraduates. I announced a workshop, (although it was paid workshop) I distributed forms in the start and announced every one will get grades on how well you perform. In the end certificate of attendance was given to those who submitted both the questionnaires. And score was announced later. You can announce for a seminar on the topic, audience will come announce for certificate and say certificate will be given after you submit the form, as it would be proof of you attendance in the seminar.

Some times even incentives dont work.. Its your luck. I would rather say the greatest drawback of these types of researches.

At Brock University, it is possible for students to earn course credit for a specific course,  as participants in a research such answering a survey.  The project must be cleared by the University Ethics Committee.  An important requirement is that students must not feel coerced into participating.  This is usually achieved by provided an alternate way to earn the points such as reading articles or writing a short paper.  Guidelines to student participation in research can be downloaded from the following page:

http://www.brocku.ca/research/ethics-and-research-reviews/human-ethics/human-ethics-policies

From student point of view, it is a learning opportunity as well as easy way to earn points.  For the researcher, it cuts down on costs.  If students answer a survey online, delays are shortened as well.

When I was working on my dissertation I offered participants money for a couple of drinks. This followed situations where potential respondents had indicated that I do soIn fact in some cases 

Have you though of include a check for $10 with your survey and thanking them in response for completing the survey. You can also ask them to return the check if they don't want to complete the survvey. The idea is to form a "regret" incentive. This approach has been shown to be very effective

Thanks Bradley.  I like the idea of a 'regret' incentive and might use it.

I should have mentioned that actually put a %10 bill is better than a check.