Question Posted 12/07/15:
I am trying to amalgamate several of the ADNI datasheets to generate a master datasheet with longitudinal data for each subject (i.e. I am using the combination of RID, VISCODE, and PHASE data to generate an identifier for each study time point for each participant).

I noticed that some of the datasheets do not have PHASE information. How can datasheets be amalgamated without knowing PHASE information? To illustrate my point here is an example- without PHASE information there is no way of knowing whether a baseline visit for RID=2 is from ADNI1 or ADNIGO?
Response posted 12/08/15 by DBA:
Each of the datasets contains both the within phase visit code (VISCODE) and the across phase visit code (VISCODE2). You may use VISCODE2 across different datasets for the purposes you've described.