"If you can't measure it you can't manage it" is a classic management platitude. I doubt Meg Whitman was the first person to say it.

Furthermore, it's completely untrue. Many things that must be managed are incompletely measurable, and almost everything in knowledge work falls into that category. See Robert Austin's excellent "Measuring and Managing Performance in Organizations" for a scientific exploration of the topic. (It's a more accessible version of his Ph.D. thesis.) His insights are applicable to more than just performance measurement.