问题
Is it possible to create a user or a session level custom dimension whose value only gets set once when the user first lands on the product?
For example, if pages of a product always set a dimension, is it possible to only consider the first value and disregard the rest (the other sets).
Is there something in GA which would enable this or is it left to the developer to write code so that the value is set only once.
回答1:
Custom Dimensions will always take the most recent value (hit/session/user).
The scope of the dimension depends on the application. If you intend to use the dimension with session level metrics (such as conversion rate) then you will need to set the dimension at session level.
If you are only curious about hit level metrics (time on page, events, page views), then a hit level dimension would be sufficient.
My assumption is that you are curious about the impact that the first interaction has on the resulting user behaviour (and potentially conversion). In this case you will need your developer to set up logic (through cookies or local storage), to only send this value only on the first occurrence. This value should then be saved as a session (or user) level dimension, which you can then use like other session level dimensions such as source/medium, device, etc. Note: if you are setting up a user level dimension, this logic needs to be dictated to your developer to ensure that the logic developed is relevant to your needs.
On a side note, this kind of logic can also be setup through the use of Google Tag Manager, as it allows for the writing of cookies/local storage values, and evaluation of these values.
来源：https://stackoverflow.com/questions/41083232/set-custom-dimension-value-only-once