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Atlas concept set search page

Could someone explain the following terms in the Atlas concept search page:
If I search osteoarthritis and RC count, it shows an RC count of 1000, and then other osteoarthritis subtypes show the RC counts. Are the patent and subtype counts independent? Can roll them up to the parent concept. If not, then how do you interpret it? Similarly, in the Hierarchy tab of the concept set, how do you explain RC, DRC, PC, and DPC? Thank you.

RC = Record Count
DRC = Descendant Record Count
PC = Person Count
DPC = Descendant person Count

These values are a heuristic about the presence of these codes in your datasource…The descendants are based on the hierarchy in the vocabulary. You can’t always roll them up to parent concepts due to the multi-parent topology of the vocabulary concept ancestor table.

You would interpret them as:
0 = this code doesn’t appear in your CDM.
< 100 = this code is rare, maybe not stress over it if you’re building a code list.
1,000,000,000 = This code seems common.

That sort of thing. I would not use any RC/DRC values as some sort of specific evidence that you can base calculations off of. They are just trying to show you what codes are in your data.