[DDI-SRG] NCube: valid N and missing N of cube (fwd)

[Wendy Thomas]

Ahh...well....this is generally reflected in your universe field (if each 
dimension has a total with a code of 0 then cell 0,0,0,0 in a 4 dimensional 
cube. Thats where the valid N should go. The information about missing or 
imputed would go in  an imputation table. The thing is, if you are aggregating 
and have missing values you generally want to do something to deal with them 
(imputation). You goal is standardly defined universe

so are they missing because they are missing by definition or just missing 
data?

Cleaning and processing of missing data comes prior to aggregation.

If you handle them like say a national statistical agency, you will have a 
separate set of tables expressing the number of  missing items and if they are 
handled by substitution or imputation. Data holes just really aren't 
acceptable. Your only other alternative is to use the 0,0,0,0 approach and 
adjust your universe to read blahblahblah who responded to each of the 
following questions OR include missing as an identifiable value in each 
dimension.

Wendy


On Mon, 8 Dec 2008, Joachim Wackerow wrote:

> I'm talking about cases not cells. Yes I'm talking about case-wise deletion 
> at crosstabs (excluding missing values). It would be nice to have the missing 
> N in addition to the table which already has the valid N (in an implicit or 
> explicit way). For example SPSS prints out the "case processing summary" with 
> valid N, missing N, and total N. Suppressing the missing values is usually 
> the default.
> 
> See attached SPSS printout sample.
> 
> Achim
> 
> Wendy Thomas wrote:
>> 
>> Are you talking about the valid number of cells in an NCube? This is in the 
>> NCube structure. @cellCount  @isClean=true implies no missing. Missing by 
>> default of the structure are identified using the attribute and attaching it 
>> to a definition of the cells.
>> 
>> Are you talking about a specific instance of an NCube in terms of the 
>> application of cell-wise suppression to specific content? (currently not 
>> doable although you can identify cell level suppression code as an attribute 
>> and additional measure)
>> 
>> Wendy
>> 
>> On Mon, 8 Dec 2008, Joachim Wackerow wrote:
>> 
>>> I'm wondering where to store valid N, missing N, and total N of a table
>>> represented in a ncube. I'm talking about the valid N and missing N of
>>> the table not just of one dimension. The total N of a table can be
>>> stored in pi:CaseQuantity, but actually this can be misleading.
>>> 
>>> Do I miss something or should this be added in a future version?
>>> 
>>> Achim
>>> 
>>> -- 
>>> GESIS - Leibniz Institute for the Social Sciences
>>> Postal address: P.O. Box 122155, 68072 Mannheim, Germany
>>> Visiting address: B2 1, 68159 Mannheim, Germany
>>> Phone: +49 (0)621 1246 262
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>>> E-mail: joachim.wackerow at gesis.org
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>> 
>> Wendy L. Thomas                          Phone: +1 612.624.4389
>> Data Access Core Director         Fax:   +1 612.626.8375
>> Minnesota Population Center              Email: wlt at pop.umn.edu
>> University of Minnesota
>> 50 Willey Hall
>> 225 19th Avenue South
>> Minneapolis, MN 55455
> 
> 
>

Wendy L. Thomas                          Phone: +1 612.624.4389
Data Access Core Director		 Fax:   +1 612.626.8375
Minnesota Population Center              Email: wlt at pop.umn.edu
University of Minnesota
50 Willey Hall
225 19th Avenue South
Minneapolis, MN 55455