VAST impressions vs. requests
Due to the way VAST requests are made, the impressions and requests we track in AdButler will not always appear consistent. This can be a result of a number of factors:
Bidding setups will request a batch of ads at once, but then only decide to display a single ad item from that batch. The ad server will count one request per ad in the batch, but only record one impression since only one ad ended up being displayed.
Incompatible file format
When a request is made for a VAST ad but the video player can't find a compatible file to play, a request will be counted but no impression will be recorded. See our file format recommendations ...
If a user leaves the page or if they experience a network connection issue after an ad request was already sent, the request will be counted but no impression will be recorded.
Depending on how frequently these events occur, the number of VAST requests may be considerably higher than the VAST impressions over the same period.