# of Impressions is low comparing to # of Filled on Facebook Audience Network

Question

In our app, we have a feed of images loaded in an ListView. These images are returned from our server. When an user scrolls down to the bottom of the page, a load-more logic would be triggered, where we will send another request to our server to ask for more content (images) to display. This is also the time when we request for one FAN ads using the Facebook SDK. If an ad is indeed returned by Facebook, we will insert it into the list of content just returned by our server. Finally, when this cell (containing the FAN ad) is in view, we would start loading the content (images and texts) of this cell.

Given we don't pre-cache FAN ad, we expect the # of Impression to # of Filled ratio to be close to 100%. However, we've been observing a ratio of around 67%.

FYI - all FAN ads referenced here are NativeAd.

Question: what happened to the 33% of the Filled requests? Somehow they are rendered, but are not counted as Impressions?

Answer 1

I am an engineer working on Audience Network. Impression for a NativeAd is logged only when the view registered for that NativeAd is viewable on screen. If the view is in the part of the list view that is not yet visible on screen, it will not be counted as an impression. (It will be counted when it becomes visible.) This should explain the difference between filled requests and impressions.