The CTR (click through rate) represents the probability that someone will click an advertisement or result on Google after they have performed a search.
In most cases, the probability that someone will click one of these links will be lower as they move down the page. So the probability that someone will click the top link on a page will be higher than the probability that they will click the second link.
Google’s organic results have a tendency to be static, with advertisers only changing position every few days if at all, regardless of how many searches are performed.
At Adthena, we have developed our own organic CTR model. The model for that assumes the same click through rates for all search terms; so position 1 on Organic is always a CTR of x and position 2 is y.
This is less complex than our paid CTR model, which uses machine learning to calculate the individual predicted CTR for every competitor in every position for all individual search terms.
Different industries have different CTR models but we have not yet included this information in our organic model, only in our paid model.