Ballot Box Stuffing occurs when an individual (respondent) submits more than one survey. This may occur intentionally or unintentionally as the result of mulitple clicks of the submit button, or actually taking the entire survey again.

We have identified several reasons for multiple submissions. In the case of multiple clicks, slow responses from the Internet may delay acknowledgement of survey submission and lead the respondent to click the submit button more than once. This appears to occur more frequently during busy internet times and with dial-up modems. If incentives are offered for survey completion, respondents may attempt to increase their probability of winning an incentive, or to receive multiple rewards. They sometimes clicking submit multiple times (or even restart the survey from the beginning multiple times to increase their chances).

By tracking these multiple responses, we have observed that most multiple submission occur at the same time and do not involve retaking the entire survey. However a few individuals will return to the survey site days later and then retake the survey again, especially where compensation is involved. It is unclear however if it is the same individual or perhaps another member of the household that makes the second response.

To control these practices, several safeguards have been implemented.

First, without anti-ballot box stuffing (ABBS) turned on, the respondent is notified that their survey has been received and they are assigned a respondent id number.

Second, if a second submit is received, they are presented with a screen that gives them the option to either restart the survey, or to retake the survey again. The restart applies where the stop-start feature has been implemented for the survey.

Third, an "anti-ballot box stuffing" (ABBS) option is available on the survey administration page. When ABBS is selected, cookies are sent to the respondent's computer when the first survey submit is received. The cookie contains information identifying the respondent and survey, and prevents retaking this particular survey.

Note that ABBS cannot distinguish between the survey owner's PC and the PC of an actual respondent. This means that if the ABBS option is in effect, you will only be allowed to complete or test the survey once. Therefore, do not activate ABBS until after the questionnaire is finalized and all testing has been done. Note that when ABBS is turned off, cookie checking is disabled and multiple responses are again permitted, even if a cookie has been placed on an individual's machine.