Tutorial: Duplicate Response Protection with Embedded Surveys

Restricting users from taking a survey more than once is called Duplicate Protection within SurveyGizmo. While it provides some protection against multiple responses from a single individual, there are some considerations that are necessary. For instance, if you are using embedded surveys, some methods of Duplicate Protection are not supported with some embedding methods. Embedding options are listed and available on the PUBLISH tab within the SurveyGizmo tool, and include: JavaScript embed, iFrame embed, and direct HTML embed.

Duplicate Vote Protection with Embedded Surveys

There are two primary types of duplicate protection for your survey: IP Based and Cookie Based protection. You can set these protections within your survey at the Pro and Enterprise plan levels by going to Edit Survey > Advanced Options. Both have their benefits and drawbacks, so let’s discuss those first.

• Cookie Based protection
  • Good for dedicated survey pages, not for embedding in multiple pages/sidebar/footer
    For one question polls, use Create Poll > Simple Poll instead for embedding in multiple pages
  • Cookie is stored on respondent’s computer, but can be cleared easily
  • Switching computers or web browsers side-steps protection
  • Embedded surveys may not accept 3rd party cookies, based on browser security settings of the respondent
  • Good for multiple users within a single IP address (schools, businesses)
• IP Based protection
  • Respondent cannot change IP address easily (possible through proxies)
  • Families and companies usually share a single public IP address, so one respondent in a company will block the survey from all others sharing that same IP address
  • Good for very diverse distribution and audiences
• URL Variable Based
  • Allows outside websites (such as Exact Target) to provide an individual response link to a survey
  • Editing the sgUID value manually would work around the issue (assuming no secondary protection within the survey)
  • If no sgUID is provided (such as clicking a link under PUBLISH tab), respondent is not blocked

While none of these duplicate protection options alone provide a perfect solution, they do offer some protection against multiple responses from a single individual. For each type of embedding, the following duplicate protection is available:

• JavaScript - IP & Cookie
• iFrame - IP & URL Variable Based
• HTML - Not compatible with duplicate protection

File Uploads Question Type

As a quick note, the File Uploads question type is only compatible with the following embedded survey methods:

• iFrame
• HTML

It is not compatible with the JavaScript embed because of the limitations (for security reasons) of the JavaScript protocol itself rather than within SurveyGizmo.

If you have any further questions, please feel free to use our community forums.