Tutorial: Duplicate Protection (Limiting One User to One Response)

Update October, 2008
The following tutorial has fallen out of date with features and the user interface of SurveyGizmo. The tutorial, Duplicate Response Protection with Embedded Surveys, discusses Duplicate Protection in detail as well and is up-to-date.

When running surveys, you often want to get as many responses as possible. But when a single person submits survey answers more than once, it may screw up your results.

That’s why SurveyGizmo offers a feature called Duplicate Protection. When you enable it, this tool limits an individual to one response. It works based on either the survey taker’s IP address or cookies on the survey taker’s machine.

Note: This feature must be implemented before launching a survey. Once in place, a user who tries to submit multiple responses will receive a message that the survey is full.

Select the Edit Survey > Advanced Options tab. Make sure the blue Advanced Options bar is open. The third option, Survey Duplicate Protection, has three radio buttons. By default, No Vote/Dupe Protection is selected.

If you select Protect Via IP, the survey will not accept multiple responses from the same IP address. If your respondents are primarily consumers, and you don’t anticipate they’ll be coming from the same IP address, you may wish to choose this method of duplicate protection.

But if you expect more than one respondent has the same IP address, a better option for you is to select Protect Via Cookie. A small cookie is placed on the end user’s computer, and the survey will recognize if the same machine tries to submit multiple responses and not allow it. Granted, this method isn’t foolproof, because some users regularly delete their cookies, but for many it is the better option.