[DDI-ADG] Concerns about nCube spec?

[Julie Linden]

Hello everyone,

I've been thinking about how to address the "aggregate" part of our 
Working Group's charge. The "Possible Configuration of DDI Working Groups" 
document that was distributed at the Expert Committee meeting in October 
states: "While considerable time and effort have already gone into the 
creation of an aggregate/tabular extension to the existing DDI 
specification (nCubes), there is concern that the aggregate model may be 
overly complex. The group needs to take a fresh look at this issue."

As someone who is just beginning to get familiar with how the current DDI 
handles aggregate data, it's hard for me to begin envisioning how it could 
be simplified or overhauled. I thought that perhaps a starting point would 
be to review what concerns have been raised. I read through the Structural 
Reform Group's postings on ezboard, and found one comment that suggests a 
concern, but doesn't spell it out:

"Logical  Physical file format mapping: How are the logical concepts in 
the DDI mapped to the underlying physical files? What kinds of physical 
file formats are there (rectangular, cards, SPSS, STATA, SAS, Census 
aggregate data, European aggregate data)? Should DDI even be tackling this 
question? There is an existing difference of opinion already regarding 
this in the nCubes specification."

Can someone on this group describe the issues/concerns explicitly? 

thanks,
Julie