The Visibility Score is the core SEO performance metric. It allows you to see, at a single glance, an accurate measurement of the overall visibility in Google on a group of keywords.
It is expressed as a percentage, representing your impression share in the organic results: how many times a user saw your website in the results page, from the total number of searches on your keywords. Note that an impression is considered when someone actually scrolled to see your website in the SERP, and not just when the SERP was loaded.
To calculate the Visibility Score of a list of keywords, we take two parameters into account: your ranking and the monthly search volume, for each keyword. Depending on how high you rank, we estimate how many of the people searching for the keyword saw your website among the search results. If you rank first on a keyword, you get a 100% impression share. The impression rate decreases until close to 0% once you rank below the second page.
Then we multiply that by the average monthly search volumes and we get the impression share, which is the Visibility Score.
Let's have a look at the example below:
It is easy to notice how the ranking of Keyword 1 is given much more weight in the combined visibility figure, due to its relatively high search volume. Thus, it is able to pull the group's Visibility Score up to 83.3%.
For reasons of simplicity, the example above refers to a group of only two keywords. But, in practice, a group might contain hundreds, or even thousands of keywords, making it impossible to analyze the daily rank change for each of them. This is where the Visibility Score comes in handy: it shows you a figure representing the aggregation of all the ranks, weighted against the average search volumes. It is to a group what the rank is to a keyword.
Since the Visibility Score is updated every day (due to our daily rank crawls on both desktop and mobile), and since it can isolate the SEO performance, it allows the correlation with the various factors influencing the rank changes, like adjustments in Google's algorithms, on-page changes etc. And in filtering out the search seasonality and trends, the Visibility Score guarantees an easy and accurate tracking of your SEO performance.
Here's a short video about the Visibility Score: