When should I use a data mapping and when should I use a rule?

If you need to create a rule on a study object, such as a form, but an item that the rule must reference is not in the scope of the study object, you have the following options:

Add the item to a data series, so you can use the item in any rule in the study.
Move the rule to a higher-level study object that includes all study objects that are needed for the rule in its scope.

There is no set guideline for which approach is better. The Central Designer application does not require you to use data mappings for rule creation, and you must weigh the benefits and limitations of using data mappings when making this decision.

Benefits and limitations of using a data mapping.
You can create the rule on a lower-level study object, thus improving the likelihood that the rule will be reused.

However, you must include the data mapping in every study that uses the study object on which the rule is created.
Benefits and limitations of moving a rule to a higher-level study object.
You can create the rule on the study object with all study objects in its scope without adding another item to the data mapping.

However, if the rule is created at a higher-level study object, the likelihood that it will be reused might be low. For example, some organizations might be more likely to reuse an item or form rather than an entire study event.
Oracle recommendation.
Oracle recommends that you create a data mapping and use it for rule creation if you use:
- Every instance of a study object in one or more rules. Add the study object to a data mapping.
  For example, you should create a data mapping if you have a repeating Adverse Event form and a rule must reference the event description or event ID from every single instance of the form.
- An item frequently in a study. Add the item to a data mapping.
- An item and a rule in many studies. Consider adding the item to a data mapping.