Why 'I'd buy that' isn't the same as a sale

Ask about the last purchase, not just the next one.

Imagine someone tells you they'd pay more for a better product. Then they reach the checkout, see a discount on their usual brand, and buy that instead. They weren't necessarily misleading you. The real choice included details your question left out.

Researchers call this the say-do gap: the difference between what people say they will do and what they actually do. A useful way to explore it is to ask about a recent purchase. What did they compare? What did they spend? Why did they choose that option?

Then ask about the new idea in a similar setting. Put a price on it. Show the alternatives. Include the option to buy nothing. You get a more useful question than simply asking whether someone likes an idea.

The same applies when you use an AI audience. Give it the real choice, not just the product description. Check its answers against customer behaviour before using them to plan sales.