Lord Kelvin - "If you can not measure it, you can not improve it."
"You can't improve what you can't measure."
Peter Drucker - "you can't manage what you can't measure"
W. Edward Deming - "In God we trust, all others must bring data."
Converse is not generally true: Just because it can be measured doesn't mean it is the right thing to improve.
W. Edward Deming - "The most important things cannot be measured."
Ability to measure shouldn't be a justification for focusing on measurements instead of trying to understand the entire problem.
Zac Brown Band - "There's no dollar sign on a peace of mind ..." - (so let's drink some beer and eat fried chicken)