BOS - Online Surveys

powerful, flexible online surveys

Pre-population – Constraints and considerations ADVANCED

There are restrictions on the way that pre-population parameters can be used in a survey, and there are also survey design aspects that you should consider when using pre-population parameters.  Some of these are listed below:


Only certain question types can be used for pre-population

Pre-population parameters can only be assigned to:

  • Free text questions.
  • Date/time questions.
  • Multiple choice (single answer) questions.
  • Selection list questions.

Duplicate option labels cannot be used

A question that has two or more identical answer options cannot accept a pre-populated answer.

Pages cannot contain only hidden questions

Your survey cannot be launched if it contains pages that your respondents may not see.  Creating a page that only contains pre-populated questions that are set to either “Always hide” or “Hide if parameter supplied” means that your respondent(s) may never see that page.  Each page must contain at least one question that is always visible.

The x1-x10 fields can only be used in the respondent list if the parameters have been assigned to a question

The x1-x10 fields in the respondent list can only be used to store information if this information is also being captured in the survey.  If you are using the x1-x10 fields in your respondent list you must assign the relevant pre-population parameters to a question in your survey.

The Email parameter requires a minimum of 255 characters

Email addresses can be up to 255 characters long.  You should not apply a character limit of less than 255 characters to a free text question that has been assigned the Email parameter.


Hidden questions

If a question is set as “Always hidden” then the respondent never sees the question and is not able to answer it.  If you have also set the question as required (mandatory) then you must provide a pre-populated answer for the question.  If you do not, any affected respondents will be unable to complete the survey.

Pre-populated questions are hidden only from the respondent when they are completing the survey. They are not hidden from view in the survey editor, nor are they hidden in the results analysis.  Additionally, if you allow your respondents to print a copy of their responses, pre-populated questions and the associated answers are always visible in the response printout, even if the questions are hidden.


When adding a pre-population parameter to a question, you should take into account the impact on any sub-questions.  If the pre-populated question will be set as “Always hidden”, this will also hide any of the sub-questions, and your respondents will therefore not be able to answer those questions.

If you have made the sub-questions required (mandatory), your respondents will be prevented from completing the survey if the parent question is pre-populated and hidden, because your respondents will not be able to see or respond to the mandatory question.

Pre-populating questions that have sub-questions should therefore be avoided as much as possible.  Alternatively, you should ensure the parent question is always visible or pre-populate the sub-questions.

Multiple choice and selection list questions

If you apply a pre-population parameter to a multiple choice or selection list question, you must ensure that the pre-populated answer matches one of the answer options exactly (including spelling, punctuation, capitalisation and spacing).

If you do not provide a pre-populated answer in exactly the right format, BOS cannot match the answer to the question and any affected respondents will not be able to access the survey.

Care should be taken when constructing these questions, and complicated answer options containing unusual capitalisation or punctuation marks should be avoided.

Validation on free text questions

It is possible to restrict the type of answer that a free text question can accept, for example to limit responses to numbers within a particular range.  If this type of restriction is applied to a question that has a pre-population parameter applied to it, you must ensure that the pre-populated answer that you supply meets the relevant criteria.

If the pre-populated answer does not meet the relevant criteria, BOS cannot match the answer to the question and any affected respondents will not be able to access the survey.


Capturing identifiable information about your respondents in the survey responses will compromise the anonymity of the response data.  For more information, please see our FAQ on respondent anonymity.

No respondent data corresponds to field xN

This is a warning message alerting you that one or more respondents does not have any information in the relevant field in your respondent list.  You do not need to take any action if the records have been intentionally left blank.

If you believe that all respondents should have a pre-populated answer for the parameter in question, export your respondent list and check for blank records.