I've looked for this one before and concluded it was a paraphrasing of a quote by Lord Kelvin.
…began his presentation with two interesting quotations that he found to be mutually exclusive. The first was by Bill Hewitt (sic) (co-founder of Hewlett-Packard): "You cannot manage what you cannot measure." The second was attributed to a sign that had hung on Albert Einstein's office wall: "Not everything that counts can be counted, and not everything that can be counted counts."
http://www.odwyerpr.com/archived_storie ... omm_hp.htm
I’m pretty sure it is Bill Hewlett, not Hewitt
"If you can't measure it, you can't manage it"~ [Tom DeMarco paraphrasing Lord Kelvin]
If you can’t measure it, you can’t manage it" ~George Odiorne .
"If you can't measure it, you can't manage it."-Greg Thurman
If you can measure that of which you speak and can express it by a number, you know something of your subject; but if you cannot measure it, your knowledge is meager and unsatisfactory."
When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely in your thoughts advanced to the state of Science, whatever the matter may be.~Lord Kelvin
"What you do not measure , you cannot control ."
"What gets measured , gets done ."