Auction statistics are an overview showing which advertisers your campaigns meet in the same auctions and how you stand against them. It contains each competitor's share of impressions, the degree of overlap with your impressions, and how often they appeared above you. In practice it serves three purposes. It reveals new advertisers who have entered the market and driven up the cost per click, even before this shows up in the overall figures. It shows whether a competitor is pushing particularly hard during a certain period or on certain topics. And it helps decide where it is worth competing and where it is cheaper to step back. Review the overview regularly, not only when performance drops.
See also: Impression share, Ad Rank, Competitor campaigns.
