Web Related Questions - How can I prevent ballot stuffing or limit people to one response?

There are several ways that duplicate responses can be reduced or eliminated. Assigning a unique identifier to each respondent is the most effective way to prevent people from entering multiple responses. Without using a unique identifier, there are no 100% effective techniques to prevent ballot stuffing. The goals of complete anonymity and one response per person are at odds with one another, so other measures are used to reduce duplicate submissions. Common techniques for preventing or identifying duplicate responses involve:

Comparing Session ID's (EZSurvey assigns these)

If a user repeatedly clicks "BACK" and "Finish" the records will have the same Session ID.

Comparing host names or IP addresses of submissions

You must have some knowledge of how these addresses are used/assigned on each network to make effective use of this technique. Since NAT (Network Address Translation) has grown in popularity, it is common for many computers to share a single IP address. Setting up the survey to automatically reject multiple responses from the same IP address is possible, but not recommended. Usually, automatic rejection will result in both the rejection of valid responses and allows people to give multiple responses by moving to a different computer.

Check for identical answers

Checking for series of data that all have identical answers to the question set. This should be used in combination with one of the other checks. Raosoft SurveyTools provides duplicate checking based on any number of questions in the form.

Also, you can remove the navigation buttons from the browser window and/or disable the keystrokes or right mouse click menu that allows going back. Do a Yahoo! search for "disable back button" for additional information.

Custom Gateway

There is another technique that involves making a gateway survey to the actual survey that accepts a one-time use password. These passwords will be logged separately from the data collected, so there will be no way to link this password with the responses.

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