Some advice to increase the likelihood that you will get honest answers to sensitive questions from your participants.
Getting honest answers to sensitive questions from your participants is a tricky issue. There are, however, a few steps you can take to ensure that your results are less biased by participants’ social desirability.
First, make sure to mention in the briefing that participants’ responses are fully anonymous. This is especially important for questions that might ask for illegal behavior such as drug abuse. The good news is: People already feel more anonymous when filling out an online questionnaire compared to face-to-face interviews.
Second, pay special attention to how you phrase your question. You can either emphasize that the phenomenon you are asking about is perfectly normal or widely spread (e.g., by referring to a newspaper or research article about it), or by pointing out at the beginning of the question that you are asking the participants for their personal opinion.
Lastly, it might be a good idea to pilot test these sensitive questions in order to see if people would actually answer them, or if you need to rephrase them.
Depending on the type of sensitive questions, it can be useful to provide contact details of certain helplines in your debriefing. For example, if your study investigated drug abuse, providing respective helpline details can make sense.