Right after you create a model, model “Settings” tab is opened:
Transactional window is a period of time out of which conversions are analyzed. Value is attributed only to sessions that lead to these conversions.
The parameter is set before model calculation, right after click on “Calculate model” button or when setting up a schedule of automatic calculations.
Conversion window is a period of time before each conversion. Value is attributed only to sessions of this period.
By default this parameter is set to 30 days. But time to purchase can be different for your project. Before changing the parameter we recommend take a look at “Time Lag” report in Google Analytics. It shows how many days pass from the first visitor's interaction to a purchase.
A few examples of how these parameters influence what sessions are get attributed value:
Field “Index of custom dimension that contains User ID” is required if Google BigQuery Export for Google Analytics is a source of your attribution model.
To check that index please open Administrator menu in your Google Analytics account and choose Custom Definitions → Custom Dimensions.
Assign value not to all the channels
There is an option to assign value of specific traffic channels to the previous channel in the conversion path. This option is described in more details in the article “Set channels that should not get value assigned”.
After you set up parameters of your model, you can proceed to setup of funnel steps.