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Define or align common data elements (CDEs). For a new data collection: define CDEs whose semantics are clear and unambiguous; for an existing data set, existing data elements can be aligned to CDEs.
Concrete example: Set of common data elements for Rare Diseases Registration.
https://datascience.cancer.gov/news-events/blog/semantics-series-deep-dive-common-data-elements
Expertise requirements for this step
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