Facebook’s advertising auction system is getting an update on the side supply side today, as the company says it is now planning to remove what it calls “short impressions” from being counted in campaigns. Now, if an ad appears on a page that a user clicks past in an instant, then Facebook won’t count it — although Facebook isn’t saying exactly how it classifies an impression as too short versus valuable enough to count.

According to the blog post today:

To improve the value our advertisers receive from our ads, we are increasing the minimum quality of an ad impression required for us to count it.  As a result, the average quality of the impressions we do count will increase overall and many advertisers will see a higher click-through-rate (CTR).

While this won’t affect CPC prices, it should mean an increase in overall CPMs due to the removal of low quality impressions.

For reference, the company’s FAQ on the topic has a bit more. Question: “What is considered a short impression?” Answer: “A short impression applies to ads that are served on pages that are quickly viewed or reloaded. We will not count short impressions in your reports.” Question: “How will my reports reflect short impressions?” Answer: “Your Ads Manager will automatically remove short impressions from your reports.”