Surveys measure opinions, not guesses
In practice, many people answer questions even though they don’t actually have a well-founded opinion.
Not out of malice, but out of politeness, time pressure, or the feeling that they have to check something off.
If the “Don’t know” option is missing, a dangerous effect arises:
Uncertainty masquerades as an opinion.
The result?
Numbers that look clear-cut but are shaky in substance.
“Don’t Know” as a Quality Filter
In surveys, “Don’t Know” is less of an answer and more of a filter.
It separates:
- People with a genuine opinion
- from people without sufficient information
This distinction is especially valuable when dealing with complex topics, new products, or strategic decisions.
After all, a small, informed sample is often more meaningful than a large number of forced responses.
The Fear of Blank Responses
Many survey creators dread high “Don’t know” rates.
Understandably so — they seem like wasted potential.
But in reality, they reveal something important:
- The question is unclear
- The topic isn’t well known
- Or the target audience is wrong
None of these are the participants’ fault; they’re valuable clues for you.
When “Don’t know” is particularly useful in surveys
- For knowledge-based questions or expert assessments
- For new topics or those requiring explanation
- For strategic or long-term decisions
- When results have real-world consequences
In these cases, this option protects your data from bias.
When Caution Is Warranted
When asking questions about opinions or attitudes where a gut feeling is sufficient
When asking questions about priorities (“Which is more important?”)
When the survey is specifically designed to shape opinions
In such cases, “Don’t know” can become a convenient shortcut and obscure genuine trends.
Better than a simple “I don’t know”
Instead of a blanket response, it’s often better to use a more precise phrasing:
- “I don’t have enough information on that”
- “I haven’t looked into the topic yet”
- Or a follow-up question: “What do you need to make a judgment?”
This way, uncertainty isn’t just acknowledged — it’s explained.
Conclusion
In surveys, the “Don’t know” option is not a sign of weakness, but of methodological maturity.
It reduces apparent certainty but increases the honesty of the results.
If you want to know what people really think, give them the option to say they don’t know (yet).
Because false certainty is the greatest enemy of surveys — not indecision.
More tips & tricks for surveys
- How long should a survey be open for responses?
- Survey or questionnaire? Find out the decisive difference!
- Evaluating surveys with easyfeedback: Effectively collect and analyze feedback
- Tips for increasing participation rates in employee and customer surveys
- 8 tips for building your questionnaire
- Tips & tricks to motivate more participants to take part in the survey
- Why you shouldn’t ask as many questions as you like in your survey
- Negative feedback after a survey: how to best deal with it!
- 7 proven practical tips for creating your next questionnaire
- Formulating texts and questions when creating your questionnaire
- Planning a survey – systematically gaining insights
- How do I create a good questionnaire?
- When is a survey truly representative?
