This is particularly true for mobile, where it&#x27;s very easy to mistakenly tap on an ad while attempting to scroll&#x2F;swipe.<p>The natural user reaction is to quickly go &#x27;back&#x27; by swiping or hitting the back button, often before promoted site has time to load and fire off its mess of tracking pixels&#x2F;javascript.<p>However, Facebook itself has tracking pixels, and are configurable such that you can optimize for visitors that reach conditions (e.g. complete a signup).  It makes much more sense to look at costs and ad performance based on these downstream metrics, vs. looking at banner ad clicks.  (As stated in the article)