[DDI-users] How to model a value with unit

[My Coyne]

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Hi Wendy,
 Thank you for your help.
 >>> I think your confusion may be in looking first at NCubes.
 This is absolutely a true statement. I wish there is a much simpler
example to show how to use Logical, physicaldata product for a simple 
 tabular report, with microdata, some codescheme if needed, and it is
not only integer. (i.e. the table should have string of text")
 Nevertheless,  I don't think my original question relates with nCube;
for that I would like to go back to this:
 Variable = Time in seconds
 > 
 > NumericRepresentation with or without a valid range and the
attribute 
 > measurementUnit="seconds"
 > 
 > 
 > Variable = Age in days
 With this design, should you have:
 variable x where measurementUnit="seconds"
 variable y where measurementUnit="hours"
 variable z where measurementUnit="days"
 I would like to have a design in which there is only one variable
scheme Age, that would contain both 'value' and 'unit'.   Would you
think this is possible, or desirable, or reasonable?  (The reason I'm
saying reasonable, because what one variable to accomodate different
unit may not be a "reasonable" thing to do in survey instrument, I'm
seeking for advice).   
	P.S.  You might have heard from Jay Greenfield that NCS (National
Children Study) is authorized to use DDI.   (I was the person who
approached you at the very beginning, in case, you did not notice :-)
) I really hope will meet with you in person and learn a lot about DDI
from you.   
 My Coyne
 mcoyne at boninc.com [1]
 (cel): 301-399-6351
 On Sat 12/02/11 11:37 AM , Wendy Thomas wlt at pop.umn.edu [2] sent:
 > My,
 > 
 > Easiest to explain with examples:
 > 
 > 
 > Variable = Gender
 > 1 = Male
 > 2 = Female
 > 
 > Make a category scheme with the following categories
 > CategoryA = Male
 > CategoryB = Female
 > 
 > Make a code scheme where
 > value = 1 category reference = CategoryA
 > value = 2 category reference = CategoryB
 > 
 > Variable = Time in seconds
 > 
 > NumericRepresentation with or without a valid range and the
attribute 
 > measurementUnit="seconds"
 > 
 > 
 > Variable = Age in days
 > 
 > NumericRepresentation with or without a valid range and the
attribute 
 > measurementUnit="days"
 > 
 > 
 > I think your confusion may be in looking first at NCubes. These are

 > aggregations and normally data that was collected as a Numeric is 
 > collapsed to groups such as age cohorts or specified ranges. In the
case
 > of a variable used as an NCube dimension the values of the variable

 > provide the intercept point along the vector of that dimension,
thereby
 > providing part of its coordinate address. The content of the data
file 
 > will be the value of the cell which falls at the given coordinate
point.
 > In addition the measurement unit in an NCube needs to be captured
as a 
 > separate variable type because the same cube could be a count of
persons,
 > a percent, a ranking, a count of adults, etc. For example the
variable 
 > describing the dimension of gender could be the gender of cats,
dogs, 
 > people, etc. The NCube describes the measure type of a specific
cell. So a
 > variable expressing a measure of a count of cats might be
 > 
 > Variable = count of cats
 > Numeric representation @measurementUnit="cats" 
 > aggregationMethod="count"
 > 
 > In a microdata variable the variable describes the value as found
in the
 > data set. In the above examples (if expressed for a case where the
gender
 > is female the time in seconds is 45 and the age in days is 92 a
data 
 > record in a comma delimited file would look as follows
 > 
 > 2,45,92
 > 
 > DDI has a number of different representation types:
 > 
 > Numeric - means the content can be analysed as a number
 > Text - content should be treated as character
 > Code - the content is a key to a specified label
 > DateTime - the content expresses a date or time and describes the
format
 > in which this is captured. The content is to be analysed as an
expression
 > of date or time rather than of a number.
 > 
 > 
 > Wendy
 > 
 > 
 > 
 > On Fri, 11 Feb 2011, My Coyne wrote:
 > 
 > > Hi,
 > >
 > > I would like to model a value that has unit, for
 > example time {value = > 2, unit = second} or timve {value = 2, unit
=
 > years}. Or age {value=1, > unit=day} etc.
 > >
 > > I was thinking of:
 > >
 > > 1. create a CategoryScheme
 > > category value
 > > category unit
 > > 2. Create a CodeScheme
 > > code for second (=1) makes reference to
 > category unit> code for minute (=2) makes reference to
 > category unit> code for hour (=3) makes reference to
 > category unit> ....
 > > ....
 > >
 > >
 > > Is this an acceptable way to model a value with
 > unit? Please help with any idea or better way to do this. Thank
 > you>
 > >
 > >
 > >
 > >
 > >
 > _______________________________________________> DDI-users mailing
list
 > > DDI
 > -users at icpsr.umich.edu [3]>
http://www.icpsr.umich.edu/mailman/listinfo/ddi-users> [4];
 > 
 > 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.e [5]
 > duUniversity of Minnesota
 > 50 Willey Hall
 > 225 19th Avenue South
 > Minneapolis, MN 55455
 > 
 > 
 > 
 

Links:
------
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[3] mailto:-users at icpsr.umich.edu
[4]
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