5 Tips to decrease lost impressions

Sortable Ad Ops, Bloggers

Too long; didn't read:

  • Create different ad waterfalls for different traffic profiles.
  • Experiment with different demand partners.
  • It might not be intentional, but if you do not follow all the rules your demand partners you are going to have a bad time.
  • Check your dashboard often, things can go wrong, stay on top of it.
  • Speed up your site.

Loss is a way of life in the ad business; not every ad impression is going to be filled. There might be a technical issue with your ad setup, no ads to be served, or simply that your site took too long to load and a user has left your site.

One of the first things to understand when talking about loss is discrepancy. Discrepancy is the result of publishers and advertisers having a different definition of what an impression is. A publisher may count an impression when an ad is being requested, while an advertiser may counts those impression only when they have been served. The difference between an ad request and an ad being served is the first loss a publisher might encounter.

At Sortable, we work hard to monitor loss across all sources and use our Ad Optimization engine to help optimize your ad stack and reduce loss. We have put together an article on how you can decrease loss and reach an audience you never thought you had.


Waterfall optimization

Waterfalls allow publishers to handle multiple demand partners, prioritizing ad impressions based on high CPM and fill rate along a chain. However waterfalls can account for between 5 and 10% of the loss for each ad request or hop along the chain. This means that the longer your waterfall, the higher the loss you may encounter. Focus on creating a shorter, more targeted waterfall with 3-4 partners maximum.

Your waterfall should start with partners willing to pay higher CPMs; these partners, however, may not have a high fill rate. A passback will move the impression to the next demand partner in your chain. You will want to prioritize partners who are willing to pay a high CPM will also have a higher fill rate. The last partner should be a guaranteed fill partner who will fill 100% of your inventory.

All ad impressions are not equal. Consider creating different waterfalls for different countries and different device types. This means that an ad impression for an iPad user in the UK could see a different set of ads than a user i on a desktop in the US.

Optimizing a waterfall is not always easy and can take a good deal of trial and error; however, the decreased loss and increased CPM are a great rewards. Take a look at our last post on how you can automatically optimize your waterfall. 

Different partners

Some demand partners will have a different focus and different targeting parameters. This means that they will analyze your visitor profile based on demographics, countries, behavior, device type, interests, and whatever other information they can come up with. Each ad network will have a different fill rate and CPM.

It is important to test different demand partners to figure out where they can fit your ad stack in. However, when you switch from one partner to another you can expect your loss to increase or decrease based on their targeting. Experimenting with multiple demand partners and optimizing their placement in your waterfall can result in a lower loss and higher CPM.


Follow the rules

Make sure your ad server is following your demand partners rules. We are not talking about wilfling committing fraud;rather, we are saying that you can optimize your traffic by following the rules to the letter.

Some demand partners will ask you to send them all your traffic and offer to sort it out for you. However, if they are not willing to fill an ad from a user on an iPhone in Hawaii, doing this will increase loss.

Preventing loss means understanding and setting the following rules with your ad server:

Frequency caps

Most demand partners have some sort of frequency caps built into their ads, meaning that an ad for Ford is only to be displayed two times per user and should never be displayed twice on one page.

Number of ads

Partners like Adsense will limit the number of ads that they will fill on a page. If you have five ad units on a page and Adsense has already filled three, they are going to reject your request.


Google Adsense will not display an ad in an iframe. If one of the demand partners in your waterfall uses an iframe, Adsense will not fill your request. This is an issue if you are using Adsense as your guaranteed fill partner.

Device type

Some advertisers will only target users on desktop or mobiles.


Where the user is from; for instance, only targeting users in western nations.

Ad size

Most ad networks will fill IAB standard ad sizes like Leaderboard (728x90), Wide Skyscraper (160x600), Rectangle (180x150) and Medium Rectangle (300x250). IBA also has rising stars ad sizes Billboard (970x250), Filmstrip (300x600), Portrait (300x1050), Pushdown (970x90), Sidekick (300x250, 300x600, 970x250) and Slider (970x90). Rising star ad sizes tend to have a higher CPMs, however they are not supported by all networks. Once you have relationships with networks that serve rising star, you will need to make sure that those requests are only sent to networks that fill those sizes.

Matching targeting criteria with a demand partner's preferences will decrease the amount of passback which, in turn, will decrease the amount of loss.

Keep your eyes on your dashboard

Regularly check your ad server and ad network to make sure that the number of ad impressions closely matches the number of ad requests.

While you do not have to do a full audit each day, spending some time once a week or once a month can help you find slow points in your waterfall and identify what is causing loss.

Speeding up your site

This is a big one; if it takes too long for your site to load and the user has either clicked back or scrolled past the ad, you will increase loss.

Major networks spend big money to decrease the amount of time it takes to load a site. Anything you can do to increase the speed of your site will help decrease loss.