Email has many advantages. It's cheap, far-reaching, asynchronous, and easy to tinker with and test. Plus, it helps phone-phobic Millennials avoid the terror of actually calling someone or risking an in-person rejection.

But one sad fact remains about many professionals' communication medium of choice -- it's wildly less persuasive than simply talking to someone face to face.

If you or other email-reliant people in your life need a reminder of this stark fact, check out a new HBR blogs post from Vanessa Bohns. In it, the Cornell University organizational behavior professor outlines recent research she conducted that offers a startling illustration of just how much you might be losing by reflexively opting for email when making requests.

How to increase your chance of failure by 34 times.

The study asked student volunteers either to ask people to complete a short survey in person or to make the same exact request (word for word) over email. Here's the bottom line result: "People were much more likely to agree to complete a survey when they were asked in-person as opposed to over email." And this finding confirms lots of previous research on the subject.

OK, sure, you might respond, but what you lose in effectiveness you make up in ease, right? But that argument falls apart if you understand the magnitude of the difference in between email and in-person asks. Email isn't just a little worse. It's 34 times worse.

That's right, according to Bohns, people are 34 times more likely to say yes to a request if it's made in person as opposed to by email. That's a gigantic difference. So ask yourself is email really 34 times easier? If not, it might be time to make that request in person.

You're wildly underestimating the effectiveness of an in-person ask.

With so much science attesting to the enormous gap in effectiveness between email and face-to-face requests, why do so many people persist in opting for email? Rejection over email stings less, but that's only part of the explanation. Ignorance is also an issue.

Participants in this study actually predicted that email and in-person requests would be about equally effective. The message that email seriously hampers your chances of success when making requests clearly hasn't gotten out. The takeaway couldn't be clearer, according to Bohns:

If your office runs on email and text-based communication, it's worth considering whether you could be a more effective communicator by having conversations in person. It is often more convenient and comfortable to use text-based communication than to approach someone in-person, but if you overestimate the effectiveness of such media, you may regularly--and unknowingly--choose inferior means of influence.

Or to put that even more bluntly, every day nearly all of us make it wildly less likely that we'll get a yes by opting for an easy email over a slightly more daunting in-person encounter. Perhaps it's time we all man (or woman) up and face our fear of real-time communication. Otherwise, we're all making ourselves wildly less persuasive than we could be.