There are about 11 million formal meetings in the United States every day—and more than half of them may be unproductive, Harvard Business School Professor Nancy Koehn told public radio program Marketplace recently.

Why? Because many meetings are inefficiently run. They don’t set or achieve clear goals. And we hold them out of habit.

There’s a real business cost to scheduling so many unproductive meetings, Koehn and others warn. Wharton researchers noted that the average middle manager spends nearly 44 hours every month in meetings; for senior executives, it may be closer to 100 hours.

The 'anatomy of  a great meeting' 

It's clear that many meetings are unnecessary. But if you do have to assemble, there are simple solutions to make that meeting a sucess.

Drawing on best practices—as well as lessons from across our own organization—my colleagues at the Advisory Board created this useful infographic to guide if you really need a meeting (and if so, how to maximize everyone's time).