What's the most important thing your start-up needs to do? You already know the answer: Make a product or service customers will buy, use, and love.

What's the most important word in that sentence?

Yes, it's "customers."

There's no debating that it's important to research what your customers--maybe you call the "users"--want. But there is a little controversy brewing over whether you should pay someone else to do it for you.

On her blog recently, Silicon Valley user-experience expert Laura Klein acknowledged that there are plenty of highly trained pros who you can pay to plumb the minds and preferences of potential customers.

"There are lots of actual user researchers with degrees in psychology and specialized training," she writes. "They are scientists in many cases."

But Klein doesn't feel these specialists are who should be tackling user research at small start-ups.

Nope, that's best left to the people actually responsible for making decisions about the product, she argues:

The reason people shouldn't hire people to do their user research is that learning about your customer is the single most important part of your start-up. If you're outsourcing that to a person who isn't directly responsible for making critical product decisions, then you are making a horrible mistake.

I see start-ups do this over and over. They hire a consultant, or even a regular employee, to come in and get to know their users for them. That person goes out and runs a lot of tests and then prepares a report and hands it over to the people in charge of making product decisions. Half the time the product owners ignore the research or fail to understand the real implications of it.

And why wouldn't they? The product managers weren't there for the process of talking to users, so they almost certainly haven't bought into the results. It's really easy to ignore a bunch of bad things somebody else wrote about your idea in a Powerpoint presentation. It's a lot harder to ignore half a dozen real users saying those things to your face and showing you problems that they're having in real life.

Instead of hired guns, Klein insists, "the right way to do research in a start-up is to have the people who are responsible for making decisions about your product intimately involved in the research itself."

But not everyone agrees with her.

Over on Women 2.0, serial entrepreneur and former director of consumer UX at Groupon, Ellen Beldner, concurs that user research is king and dismissing its findings is poison for start-ups, but she comes to a very different conclusion about whether hands-on participation is likely to make reluctant founders more open to research.

"There are personality traits common to many CEOs, start-up founders, and product managers that make them more or less incapable of listening deeply to their users."
--Ellen Beldner, serial entrepreneur

"There are personality traits common to many CEOs, start-up founders, and product managers that make them more or less incapable of listening deeply to their users," she writes. "Strong leaders have to believe in their vision of the world and rally others to it. To be an effective user-centered researcher… you have to be willing to see the world as it is, not as you want it to be."

A tenacious but inflexible founder, in other words, is a tenacious but inflexible founder. If he or she is unwilling to listen to others and modify his or her vision, it's going to make little difference whether the insights are coming through an intermediary or being observed directly.

Do you think it matters who conducts user research? Should it be kept in-house or outsourced?