Why doesn't Facebook allow for CPI optimization at the start of a campaign?

Question

I'm trying to optimise a campaign for installs (desktop product), and thus far set up the campaign up with conversions as the campaign goal, with conversion = install, and pixel tracking installs.

But then when I go further in the campaign the only option I have for when I'm charged is Impressions. I thought that I would be charged when Facebook generated an install? Could anyone shed light on how this works, and the optimal way to set this up, much appreciated.

Answer 1

You need to generate some number of installs before Facebook will allow you to start optimizing for install events. After a while, you'll see "Installs" in the list of events for which you are charged.

With no information about how your ads perform with respect to driving installs -- that is, Facebook doesn't yet know how many times it will have to show your ad per each install generated -- Facebook is only willing to charge you on the basis of impressions. Once it gathers more data about your ads' performance for the defined audience segment, it can estimate a conversion rate and work that into a delivery volume.