Which object should I add a rule to?

A rule that is part of a study object can refer only to:

The study object and its children.
Properties and values of the study object and its children.

Tips:

The child items of a compound item are in the scope of the compound item.
If a study object falls outside the scope of a rule, you can:
- Create the rule on a study object that is higher in the hierarchy and that has the necessary study object in its scope.
- Move the necessary study object within the scope of the study object on which you create the rule.
- Add the study object to a data series. Study objects that are part of mappings can be included in any rule in a study.
To allow for reuse, create data-entry rules on the lowest-level study object that is reasonable based on scope requirements. For example, if an item requires a range check, create the range check on the item, not on the form that contains the item.
Do not create all rules on the study design. Although all study objects in the study are in scope, you cannot reuse the rules because you cannot reuse study designs.
If one or more study objects are outside the scope of a study object, we recommend creating the rule on a higher-level study object that has all required study objects in its scope.
If you choose this option, the data-entry rule might be less likely to be reused because it is created on a study object that might not be reused in many other studies, but you are no longer limited by the scope of a particular study object.
As early as possible, plan the study object on which every rule will be created.
For example, if a study event contains two forms, and you have a rule that requires data from both forms, the scope of the rule will allow you to create the rule on the study event or a higher study object.
A workflow rule is part of the workflow it is created in. If you want to use the logic of a workflow rule in multiple workflows, you must create it in each workflow separately.