[DDI-users] Group vs Universe

My Coyne mcoyne at boninc.com
Thu Jan 27 14:57:04 EST 2011


Hi DDI Community,

After reading and viewing the xsd for group and universe concepts, I find that I don't have a clear view of the these two 
concepts.  Would someone please  give me a better understand of both of these in comparison.  

1.  I understand that group is used to group StudyUnits  and subgroups (assuming that subgroups are not study units)
      -- Grouping factors (differentiators) can be: time, instrument, panel, geography, datasets, language
2.  I understand that Universe is an attribute of StudyUnits

I would like to present a fictitious scenario in helping me solidifying the concepts.  

StudyUnit A
      Universe A: all families of the USA
     Timeframe:   1970 - 2010
      In this study data collected are: marital status, education, incomes, geographical residence, religions, political affiliation for 
both parents and children

StudyUnit B
      Universe B: All families of the USA who have child/children diagnosed autistic within the spectrum 
      Timframe:   1990-2010
      In this study similar data as in StudyUnit A are collected with additional information for autistic diagnosis and genotypes of 
the children. 

Using Grouping and/or Universe concepts, Could I then retrieve datasets that contains 
(a)  information that intersect of the two universes  (of studyA and StudyB)
(b)  information about the families that do not have autistic children
?

Thank you for your help. 




I would like to retrieve two datasets D1: with all children of the USA 

My Coyne
mcoyne at boninc.com
(cel): 301-399-6351






More information about the DDI-users mailing list