The Say/Do Gap: Why Stated Preference Isn’t the Whole Story
What people say matters. What people do matters too. The two do not always align. Understanding that gap is often the difference between measuring an opinion and understanding a choice.Treat stated preference as one source of evidence, not the final answer. Where behaviour matters, measure behaviour directly whenever possible.
The gap between the survey and the shelf
Answering a survey question is different from making a real-world choice.
In a survey, respondents have time to reflect, compare options, and explain their thinking. Real decisions are often made under very different conditions, with less attention, less deliberation, and more competing influences.
As a result, what people say they prefer and what they ultimately choose do not always match. This difference is often referred to as the say/do gap.¹
It is not that people lie
Stated responses provide valuable information about beliefs, intentions, and perceptions. The challenge is simply that describing a preference is not the same thing as expressing it through behaviour.
People are often better at reporting what they think and feel than explaining every factor that influenced a choice.² A survey captures what people say. Behavioural measures capture what people do. Used alone, each leaves part of the picture unseen.
What to do about it
The solution is not to abandon surveys. It is to complement them with behavioural measurement.
Timed choices, reaction-time tasks, and other behavioural measures provide a different form of evidence. Used alongside stated responses, they help distinguish between what people say they prefer and how they actually respond.
When the two agree, confidence increases. When they diverge, the difference itself can be informative. It can reveal barriers, tensions, or considerations that would otherwise remain hidden.