You should think of impression share as a serving bowl of tasty punch at a party. That full punch bowl represents the overall impression share (ultimately the total number of chances you have to display your ad to a potential customer) that’s available at any given time. You and all of your competitors want a glass. The more glasses you obtain, the more of the overall impression share you’re drinking. When you set up metrics, you’re able to measure that amount you’re drinking as compared to your competitors. This punch is delicious and you want as much as possible! The same principle applies with your search ad campaigns and the actual number of online impressions you can obtain. You want to have the highest level of exposure among the other players in the online market space.
Impression share is the number of impressions you’ve received over the duration of an ad/campaign’s run then divided by the number of total impressions you were eligible to receive. There are a variety of metrics you can set that will help you get a sense of how your impression share stacks up against your competitors.
Search impression share allows you to see the number of impressions you have obtained on the Search Network then divided by the approximate number of impressions you were eligible to receive. Display Impression share is the same except for it measures impressions received on the Display Network vs. the Search Network.
There are also ways to track when your ads weren’t running to due to lack of budget. Search Lost IS (budget) actually provides that percentage of time that your ads weren’t run on the Search Network due to insufficient budget settings; however this information is only available at the campaign level. Display Lost IS (budget) shows the same percentage of time lost due to budget restraints; however it refers to the Display Network.
Search Lost IS (rank) and Display Lost IS (rank) show a similar metric however, this measures the percentage of time your ad was not run due to poor Ad Rank on the Search and Display Networks. You should note that if your budget lapsed at any point during the date range being measured, you will not see the IS (rank) settings in your reports. This will be trumped by the IS (budget) metrics.
The last metric you can utilize is Search Exact Match IS which measures the number of impressions you obtained divided by the potential estimated impressions available on the Search Network for search queries that matched your keywords exactly, or very closely.
These metrics reports can easily be referenced in the Campaigns tab (or Ad Groups tab depending at which level of data you’re looking to observe) of your AdWords account. Simply login and access your Campaigns tab. Next, click the button labeled “Columns” (located above your statistics table) and choose the “Customized Columns” option from the menu. This is when you’ll decide which of the aforementioned Impression share columns you’d like to analyze. After you click “Save”, the impression share columns that you’ve selected will automatically appear in your reports moving forward. It will become a part of your default statistics table. You can download the data from AdWords by clicking the download button (designated by a down arrow).
For the most up to date metrics, be sure to check after 1 PM PST as this is when data is updated on daily basis. There is a historical archive of impression share data available dating back to October 2012. Be sure to use this to your advantage to ensure that you’re not missing clicks due to insufficient budgets or ad ranks. This should also give you a pretty good sense of how your ads are performing in relationship to key competitors which can help you strategize in the long run.