Impression share data, specifically Lost Search IS (ad rank), can help you identify the percentage of time that your ads weren't shown on the Search Network due to Ad Rank in the auction.
What you can do
To minimize Lost Search IS (ad rank), improve your ad quality and your bids. Impression share data may not populate if your campaign did not generate enough traffic.
Need something else?
Check other common reasons why your campaign performance is fluctuating.
