Money.
The unit of measure that will matter to most audiences denominated in a currency.
Certain measures, like time, reach, audience, share, and pure counts of both observed behavior and stated intention, all have their places. They are means to an end. The reason why you care about reach is to make money. The reason why you care about the conversion rate is to make money.
Money is the unit that ultimately matters. The sooner marketing scientists accept that profit is the ultimate dependent variable, the sooner they can be really successful.
