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In most cases, it is adviceable to just stick to the original depth of navigation. Depending But depending on the source format the data came from, this can lead to very deep hierarchies. Examplary for an ODM import, one will find seven levels of hierarchy for a clinical trial:

1. Study
   1. MetaDataVersions
      1. Events
         1. Forms
            1. ItemGroups
               1. Items
                  1. CodeLists

This 

Some levels can be simply deleted, e.g. if there is only one MetaDataVersion or one event, they can be spared.

Another idea is to abandon hierarchy levels that where useful for data collection, but not for presentation. More than 250 concepts, on the other hand, should not be listed under a single i2b2 folder for reasons of usability. 

Splitting large value sets without natural hierarchy

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