Most analytics tools use a very simple data model to organise the data they collect. In the case of Google Analytics, the model is organised around three elements: users, sessions and interactions.
- A user is a visitor to the website or application we want to measure.
- A session corresponds to the time spent by this user on the website or application.
- An Interaction is what the user does on the Web or application.
Google Analytics data hierarchy
We can define these three elements as a hierarchy in which if we take the example of a physical clothing store, i.e. a shop, we would see that there are customers who come in once and others who come in regularly.
On each visit, customers can interact with the staff, for example to ask if a garment they have seen advertised has arrived. On another occasion, the customer will arrive, choose the garment, try it on, and buy it.
In the first case we will see that there have been two interactions (enter the store and ask for the garment) and in the second case there have been four interactions (enter the store, choose the garment, try it on and buy it).
Like a clothing shop, a website has visitors (users) of which some only visit once and others several times. For Google Analytics, each visit is a session (later we will see how GA identifies the same user in several sessions). The important thing to remember now is two things:
- Users and sessions are related to each other, just like the customers who enter the clothing store and the number of times they visit it.
- Analytics is able to distinguish repeat users across multiple sessions in the same way that store clerks are able to recognize repeat customers.
A store visit is made up of interactions, such as choosing a model or paying, in the same way as a session on a website or an application.
For example, a user enters a website and visits only the home page and leaves, in this case, we would have a session in which a user has made an interaction with our website, in this case a page view.
Let's suppose that in another session, the same user visits our home page, goes to the detailed page of an article and buys it. In this case, the user would have made three interactions (two page views and one purchase).
In Google Analytics, each interaction is considered as an outcome that can be, for example, page views, events, transactions... and is collected separately. Each interaction is what we call a hit.
In summary, we have seen that each interaction we measure with Google Analytics belongs to a session and that each session is associated with a user.
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