Last updated on 8.7.2024
When you select a “Scope” for a custom dimension in Google Analytics 4 (GA4), it is important because it defines how data will be aggregated and reported.
Differences between the various options
Item
Refers to a dimension that changes with each interaction with a specific item. For example, if you want to track the name of the product purchased in each transaction, or the category name of a page each time it is viewed.
Event
Refers to a dimension that changes with each event. For example, if you have an event that is sent each time a user clicks a button, and you want to know which button was pressed.
User
Refers to a dimension that is related to a user and does not change all the time. This could be, for example, the type of user (new or returning), the user’s gender, or any other characteristic that you want to attribute to the user over time.
Conclusion
For example, if we want to track the name of the category every time a category page is viewed, then “Item” seems like the correct choice, because each page view is an interaction with a specific item (the category).
If we had chosen “Event”, the dimension would change with every event, and if you had chosen “User”, then the dimension would attribute the category name to the user and not to the specific page view.
Essentially, the scope selection relates to the level of granularity with which we want to report the data (for category pages, it appears that the “Item” scope is the most appropriate).