Search depth is a metric value that is collected by Google Analytics Site Search reports. Search depth includes the number of subpages that are viewed by a user after a search query. It is thus a metric, which provides information about the use of the internal search of a website and indicates optimization potentials in the information architecture. Any term entered in the search field can be viewed as user interest. When users find what they’re looking for, they reach their destination and the website’s joy of use is accordingly high. If this is not the case, the data from the site search reports can be used for optimization to provide users with content and products that interest them.
The search depth value is the average number of pages that are viewed after a search query. It is calculated as follows:
search depth = The sum of the search depths of all search queries / (search transitions + 1)
If a user enters three different search queries in three different sessions and then looks at two results pages after each search query, the results pages are first added. The next step is to add the sessions in which a search query took place. Finally, the first sum of all result pages is divided by the sum of the sessions, since search transitions are defined as individual searches in a session.
(2 [product] + 2 [product] + 2 [product]) / (1 [session 1] + 1 [session 2] + 1 [session 3]) = 2.0
The site search reports can, of course, refer to other collected metrics. For example, the number of all searches, sessions, or the number of pages viewed. The lower the depth of the search, the more likely it is that the user has found what they were looking for.
If a user enters a term into the internal search for a website, this entry is recorded by site search tracking, which must be set up beforehand. Google distinguishes certain dimensions in order to separate the phases of a search.
The dimensions allow a more detailed look at the use of the search function. How long do users stay on the website after a search? What subpages do they visit and how many? The answers to these questions can be used to assess how effective a search is on a website. However, for a more detailed analysis, the data in the Site Search reports should be considered in combination. Only an overall picture of the different metrics and dimensions allows a substantive analysis of the findings in order to be able to derive concrete recommendations for action.
Google itself recommends five questions that simplify the interpretation of the metrics in the Site Search reports:
Search depth and other KPIs in the Site Search reports can be used to analyze the use of a website’s internal search. This data allows a deep insight into the interests of users and user groups especially in the case of larger on-line shops and editorial websites with a lot of content. On the one hand, the search terms indicate these interests and on the other hand the data serves to understand the user behavior with regard to the user experience and usability of the website. Successful and unsuccessful searches can be analyzed as well as content search terms.
The entered search terms are also used for optimization in a next step. Certain search terms that do not yield results can be used in the creation of content or the arrangement of the information architecture (for example the hierarchy of the product categories). Frequently typed search terms can be used as indicators for interesting products or content ideas in order to increase user satisfaction and conversions. When users reach their destination on the website and find what they’re looking for, the internal search can be considered effective and this naturally affects the sales of a website. According to the experience, up to 25% of users use the internal search function.