I currently spend $X,000 per day in advertising on facebook. Their reported clicks barely match up within an order of magnitude.

I've spent 4 days investigating this, so it's worthwhile to share the data.

For every 100 clicks I purchase, at a strong CPC ($0.10 - $2.00 CPC), I have found: - GA tells me i got between 40-60 sessions - piwik tells me ~70 - server logs show that page was requested ~400x (not indexed, a FB-only lander). I have IP and UA recorded, and both are rotated. My guess is that FB preloads the HTML LP when the impressions shows from mobile, so the browser is primed to quickly load assets (w/o sig resources to d/l images/etc -- just request the page that initially loads all that)

My point is attribution for conversions and link clicks is hard.

Any marketer worth their salt avoids the thought of "I paid for 10 clicks but GA only shows 6".

A better marketer thinks, "I paid $660 to acquire 2 customers. Is that acceptable?"