Sergio Zyman was VP of marketing at Coca-Cola during 1985 during one of the biggest marketing flops in business history: the introduction of New Coke. 

Zyman recalls in his book, The End of Marketing As We Know It, that it all came down to failing to ask a single question as they interviewed test customers:

"We gave them samples of various reformulations of Coca-Cola and tested them against the old Coke and also against Pepsi. We also asked them: ‘What would you do if we gave you a product that tasted better than Pepsi, but still was a Coke?’

They told us, ‘I would buy it.’

‘Would you like it?’ we asked.

‘Sure I would like it,’ they said.

The problem was that even though we were asking them the right type of research questions, we didn’t ask The Question.

In truth, the only question we really needed to ask was:

‘If we took away Coca-Cola and gave you New Coke, would you accept it?’"

When "New Coke" came to market, the public answered that question with a responding, "NO WAY!" and sent a multi billion-dollar corporation stumbling down a rocky path.

The next time you do research on your customers’ needs, remember, one question you miss can make a huge difference and there can be a big differnce between what a customer says they want in a survey, and what they might actually do.