I would recommend you first select a reasonable time frame, say 3 months (this depends on traffic volumes, allow for statistical significance). Then do a campaign export, use a pivot table to pinpoint the exact placements which are under-performing and then exclude them.
Unfortunately, three months represents a lot of lunch and is way too long to wait for most campaigns – sites and apps which don’t perform well on the Display Network for a particular campaign can usually be spotted within a few weeks, if not days depending on budget. Personally, I’ve never found it necessary to go to the effort of a pivot table. The online editor has usually been more than adequate for effectively identifying sites and pages that have performed well or badly and adjusting bids or excluding them entirely if necessary. It might be quicker in the offline editor though, should Google see fit to update it sometime with this functionality.
Seems that this no longer works. We have ‘adsenseformobileapps.com’ as a campaign excluded placement for all our campaigns, and mobileapp traffic has shown up again in all our display campaigns.
That’s a little odd, Tom. It definitely worked for us on a number of campaigns. Did you manage to fix it, or would you like us to take a look for you?