A few days ago, I wrote about the Fundamental Attribution Error. It’s when people place the motives for behavior on an individual’s character even though the environment is likely the most important driver.

Today, let’s discuss the Fundamental Conversion Error. It’s more straightforward than the Fundamental Attribution Error. Conversions don’t sell cars. Even though many would tell you that they do—err, statistically speaking, they don’t.

Making resource decisions—read: spending your advertising dollars—based solely on conversion metrics is essentially the equivalent of the warning sign placed on stock purchases. In either case: “Past performance is NO guarantee of future results.