Don't hire a marketer unless they keep a calculator on their desk

Marketing is an inherently analytical field:

"We undertook the following X activity, with the hopes of achieving Y result. We will have some measure to check whether or not we have achieved Y. If we don't achieve Y, we'll take a closer look at X to see where we went wrong."

That last part is the what some marketers like to skip. "If we don't achieve Y, we'll take a closer look at X to see where we went wrong." No one wants to fail, especially if their employer doesn't encourage failure. So how do you ensure you don't fail? Don't measure! As without measurement, neither success or failure is possible.

Not collecting and analyzing results has nothing to do with marketing medium, style, or just plain being bad at math. Not collecting results is a reflection of the marketer's desire not to be seen as a failure.

That's why so many ad agencies do a poor job of measuring their own campaign's success.

My advice? In general, you probably shouldn't hire someone if their main goal is not to be seen as a failure. They tend to work hard at maintain the status quo, which itself has a tendency to remain unchanged. Hence, why pay extra?

Recognizing a mistake isn't a bad thing. Having a calculator on your desk doesn't make you uncreative.