Along with interface updates, Google recently added three metrics to the AdSense ad Review Center.
Impression score indicates whether an ad has a high, medium or low number of impressions per day compared to the other ads on your site.
Serving status identifies whether an ad is active (recently received impressions) or not. If an ad is active, it’s more likely to still appear in the next few days. If an ad is inactive, it could still show again, but the longer it remains inactive, the less likely this will occur.
Historical trend shows whether the number of impressions per day for an ad has recently increased, decreased or remained stable, according to Google’s historic data.
Google also added a “Find Related Ads” link to show ads are that have a similar destination page. You can then choose to allow or block the related ads in the Ad Review Center.