Why Search Impression Share is Overrated in PPC

Is it better to be a big fish in a small pond, or vise versa?

When in comes to search impression share (SIS) there are many contrasting beliefs on what’s the best strategy to optimization towards. Do you want to own a high percentage of small market? Or would your business benefit by carving out a small portion of a large industry? Typically these are the questions we’re faced with while managing our clients – but first we need to understand what SIS is before making a recommendation on how to effectively utilize this metric.

What is Search Impression Share?

As defined by Google, the SIS is “the number of impressions you’ve received on the Search Network divided by the estimated number of impressions you were eligible to receive.” In other words, how often were your ads served up on the search results page (or when your keyword triggered an ad) when that ad or keyword was relevant to the searcher’s query? The key to understanding SIS is by understanding that it’s based on the number of impressions you were eligible to receive. How often your ad is shown depends on your ads’ targeting settings, budget, approval statuses, bids, and quality scores.

The Common Misunderstanding

Our friends over at RepriseMedia created an awesome article highlighting some of the issues related to impression share, and we feel they were spot on with their analysis. Often times we find that clients misinterpret this metric by assuming a 40% SIS is indicating they are only showing ads every 4 out of 10 searches – which isn’t necessarily the case. SIS is dependent on your account’s eligible impressions rather than actual market search volume.

In other words, if you have lots of negatives, conservative campaigns settings (standard delivery vs. accelerated), only exact match keywords or just a small geographic area in which you’re targeting, your SIS may be pretty high but you’ll only reach a few users. In contrast, if you target the entire country, you may not show in every auction (low SIS) but your impressions may actually be greater than the narrower strategy. Here at LionKlick, we explain this concept during our training for new hires using the the “100% of 10 vs. 10% of 1,000,000” concept – which would you rather have? While having a higher SIS is great, you may actually be missing impressions, hurting volume, limiting brand exposure, and ultimately driving fewer conversions.

We found an interesting tweet the other day where someone was confused as to why impressions dropped despite having a 99% SIS. While there are many reasons to explain why, we believe the targeting settings are more restrictive and the ads are ultimately showing up in less auctions. We think some of the campaign settings have changed, effectively reducing the number of impressions the account was eligible to receive.

So, how should we use SIS?

When it comes to SIS, we feel the best strategy depends on the goals and objectives of your client. You should clearly and effectively communicate with each decision maker to discuss the pros & cons of implementing each strategy related to SIS. Casting a smaller net will allow you to dominate a specific geographic area, such as a client’s backyard or PMA. However, targeting more users across a larger area may stretch your marketing dollars thinly but you’ll almost always get in front of more users with a lower CPC – but you won’t effectively be penetrating any particular location or area. Depending on the goals of your client, it may be more beneficial to optimize towards higher volume and more exposure, ultimately translating to a lower SIS, which is actually okay at times.

Best of luck optimizing! 🙂