Is the AgeAtFirstClaim variable in Members.csv the age of the member in Y1, or their age in the year of their first claim?

In other words, say you had two members, both with AgeAtFirstClaim = 20-29

The first member has claims in Y1,Y2,Y3, so they are presumably aged 23-32 in Y4

The second member only has Y3 claims. In Y4 are they aged 23-32 or 21-30?

I would assume 21-30. There's nothing in the data dictionary implying that those with first claims in Y3 have Y1 age information. Instead, it says the age comes from the first claim.

@mkwan

It is based on their first claim in between Y1 and Y3, so i'd say 21-30. A similar post over here:

http://www.heritagehealthprize.com/c/hhp/forums/t/578/age-at-first-claim-how-is-it-handled-over-time-and-category