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.pdma.org/visions/oct95/fe.html
http://www.odwyerpr.com/archived_storie ... omm_hp.htm
I’m pretty sure it is Bill Hewlett, not Hewitt
http://www.hp.com/hpinfo/abouthp/corpobj.htm
"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."
~LORD KELVIN
[another version]
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 ."
~TOM PETERS
"What gets measured , gets done ."
~TOM PETERS