In the fall of 1999, John Doerr met with the founders of a start-up whom he’d just given $12.5 million, the biggest investment of his career. Larry Page and Sergey Brin had amazing technology, entrepreneurial energy, and sky-high ambitions, but no real business plan. For Google to change the world (or even to survive), Page and Brin had to learn how to make tough choices on priorities while keeping their team on track. They’d have to know when to pull the plug on losing propositions, to fail fast. And they needed timely, relevant data to track their progress — to measure what mattered.