I enjoyed this quote/anecdote from Fast Company on Larry Page:

So Mayer approved an “experiment” in which for several months about one of every 10,000 search requests would return a page with more than two ads at the top. As Mayer had suspected, users seemed to shun pages plastered with five ads. But the test also proved that people would tolerate more than two ads, and Google now runs up to three ads at the top of its pages. “No idea is a bad idea until the data prove so,” Knapp says, repeating what is likely the company’s second-most-popular mantra after “Don’t be evil.”

Even Page has proved willing to reverse himself if the numbers don’t bear him out. “Larry would wander around the engineers and he would see a product being developed, and sometimes he would say, ‘Oh, I don’t like that,’ ” recalls Douglas Merrill, who served as Google’s chief information officer until 2008. “But the engineers would get some data to back up their idea, and the amazing thing was that Larry was fine to be wrong. As long as the data supported them, he was okay with it. And that was such an incredibly morale-boosting interaction for engineers.”

I know many great leaders who are ok with being proven wrong and more than a few bad ones who are not.