One of the great things about online surveys is that you can create a world where free will no longer exists. Or in other words you can choose to make your survey questions mandatory or optional. This power should be used wisely though as although you can make your survey questions mandatory it is a far harder exercise to make your survey mandatory and making survey questions mandatory can be a great way of increasing your survey dropout rates. I thought it was worthwhile investigating then when questions should be mandatory and when caution should be applied.

To begin with it is probably useful in determining what a mandatory question actually is. A mandatory question is when the survey respondent is forced to respond to the question.  If no response is received then the respondent is not able to proceed with the survey. Generally this is achieved by a simple piece of javascript which in practive is as simple as ticking a box marked “Mandatory”. So far it sounds pretty good. Mandatory questions mean that all your survey questions will be answered – what could be wrong with that? In practice a lot -the major downside is that making questions mandatory can bug the hell out of your respondents and cause them to simply dropout of your survey.

A good rule of thumb is the more mandatory questions your survey has the higher your survey drop-out rate will be. All that is achieved by a high drop-out rate is a high non-response error, which is something which should be avoided at all costs. It pays then to seriously consider when you should make questions mandatory.

• Screening Questions

Often when conducting your survey you have a target segment in mind. You may wish to research all females aged  between 18 – 40. It makes sense then that any screening questions are made mandatory. In this example gender and age are required to be mandatory to ensure you get to speak to the right people. i.e. females aged between 18-40

• Branching Questions

Branching questions are when the respondents answer to a question sends them off in a particular direction whilst a different response will send then in a different direction of the survey and asked another question. It is essential to make branching questions mandatory otherwise the survey will not know where to send them and your survey respondents will be stuck in survey limbo for ever (not a nice place). 

• Essential Questions

Essential questions are those questions that you really need an answer to. You really need to take a step back on this one. If you wrote the survey you are likely to believe that all questions are essential. Before you make all questions mandatory take a long hard look at the survey questions and ask yourself what if any damage will be done if the respondent chose not to answer the question. If you can live without the data then give the respondent the choice (another note, if you can live without the data ask yourself if the question is required at all).

The three tips above are pretty good guidelines to keep in mind when considering if you should make your questions mandatory. But like most thing there are a couple of mitigating factors that should also be considered when making this decision.

• Length of Survey

If your survey is short you are more likely to be able to get away with mandatory questions than if your survey is long.

• Relationship with respondent

If you have a close relationship with your respondent’s i.e. if they are staff members then you are more likely to be able to get away with mandatory questions.

• Incentives

If you have some generous incentives for respondents the above rules for mandatory questions. The rule of thumb with incentives and respondents is the greater the level of incentive the more your respondents will be willing to put up with.

So while mandatory questions are pretty useful to ensuring you get the data you need they also have the potential to really bug your respondents. In a way mandatory questions are a lot like drinking – moderation is the key!