InstanceVariable

Package: 
Version: 
0
Is Abstract: 
no
Is Pattern: 
no
Definition: 

The use of a Represented Variable within a Data Set. The InstanceVariable describes actual instances of data that have been collected.

Explanatory Notes: 

The InstanceVariable class inherits all of the properties and relationships of the RepresentedVariable (RV) class and, in turn, the ConceptualVariable (CV) class. This means that an InstanceVariable can be completely populated without the need to create an associated RepresentedVariable or ConceptualVariable. If, however, a user wishes to indicate that a particular InstanceVariable is patterned after a particular RepresentedVariable or a particular ConceptualVariable that may be indicated by including a relationship to the RV and or CV. Including these references is an important method of indicating that multiple InstanceVariables have the same representation, measure the same concept, and are drawn from the same Universe. If two InstanceVariables of a person's height reference the same RepresentedVariable. This indicates that they are intended to: be measured with the same unit of measurement, have the same intended data type, have the same SubstantativeValueDomain, use a SentinelValueDomain drawn from the same set of SentinelValueDomains, have the same sentinel (missing value) concepts, and draw their Population from the same Universe. In other words, the two InstanceVariables should be comparable.

Example: 
1) Gender: Dan Gillman has gender <m, male>, Arofan Gregory has gender<m, male>, etc. 2) Number of employees: Microsoft has 90,000 employees; IBM has 433,000 employees, etc. 3) Endowment: Johns Hopkins has endowment of <3, $1,000,000 and above>, Yale has endowment of <3, $1,000,000 and above>, etc. Two InstanceVariables of a person's height reference the same RepresentedVariable. This indicates that they are intended to: be measured with the same unit of measurement, have the same intended data type, have the same SubstantativeValueDomain, use a SentinelValueDomain drawn from the same set of SentinelValueDomains, have the same sentinel (missing value) concepts, and draw their Population from the same Universe. In other words, the two InstanceVariables should be comparable.
Property: 
NameCardinalityDatatypeDescription
variableFunction
0..n
Immutable characteristics of the variable such as, geographic designator, weight, temporal designation, etc.
physicalDataType
0..1
The data type of this variable. Supports the optional use of an external controlled vocabulary.
platformType
0..1
This should match a platformType of the RepresentedVariable on which the InstanceVariable is based (if one exists). It is drawn from the same external controlled vocabulary used by the RepreentedVariable's platformType. A sample list for the external controlled vocabulary is: A sample list would be: • BlankString - A Blank string indicates missing. Comparison is based on lexical order. • EmptyString - An empty string indicates missing. Use in comparisons returns missing. • Rstyle - Codes drawn from NA and the IEEE 754 values of NaN -Inf +Inf. Comparisons return NA. • SASNumeric - codes drawn from . ._ .A .B .C .D .E .F .G .H .I .J .K .L .M .N .O .P .Q .R .S .T .U .V .W .X .Y .Z Sentinel code treated as less than any substantive value • SPSSstyle - System missing (a dot) a set of individual values drawn from the same datatype as the SubstantiveValueDomain, and a range of values drawn from the same datatype as the SubstantiveValueDomain. Comparisons return system missing. Some functions substitute with valid values (e.g. SUM replaces missing values with 0) • StataNumeric - codes drawn from . ._ .A .B .C .D .E .F .G .H .I .J .K .L .M .N .O .P .Q .R .S .T .U .V .W .X .Y .Z Sentinel code treated as greater than any substantive value • Unrestricted - No restrictions on codes for sentinel values. Use in comparisons is indeterminate.
Relationship: 
NameTarget ObjectDescriptionSource cardinalityTarget cardinalityRelationship type
measures
Set of specific units (people, entities, objects, events), usually in a given time and geography, being measured. Can be a specialization of the Universe measured by a related RepresentedVariable.
0..n
0..1
Neither
basedOnRepresentedVariable
The RepresentedVariable that can be shared by multiple InstanceVariables. Indicates comparability in substantive representation, Universe, and indirectly ConceptualDomain. If a relationship to a RepresentedVariable is defined there should be no relationship to a ConceptualVariable.
0..n
0..1
Neither
basedOnConceptualVariable
The ConceptualVariable that can be shared by multiple InstanceVariables. Indicates comparability ConceptualDomain and UnitType. If a relationship to a RepresentedVariable is defined there should be no relationship to a ConceptualVariable.
0..n
0..1
Neither
takesPlatformSpecificSentinelValues
The association to the possible sentinel (missing) values.These will be specific to one software platform.
0..n
0..1
Neither
sourceCapture
The source of capture for the values that populate this InstanceVariable. This may be any class using Capture as an extension base, currently RepresentedQuestion and RepresentedMeasurement. This is the direct source of capture for the content of the data. If a transformation is required the source is not multiple captures but the transformation.
0..n
0..1
Neither
generatedBy
If generated directly through fielding an instrument use the instrument component containing the capture for the values that populate this InstanceVariable. A Capture is reusable and therefore it is important to know the specific use of the Capture within an Instrument. This may be any class using InstrumentComponent as an extension base, currently InstanceQuestion and InstanceMeasurement. If the content of the InstanceVariable was generated by a computation or other form of transformation with data processing, use the ComputationAction or similarly appropriate subclass of Act. If a sequence of Acts resulted in the InstanceVariable content indicate the final Act.
0..n
0..1
Neither
Is extendable: 
GSIM: 
Instance Variable
Is property: 
0
RDF Mapping: 

Comments

jon's picture

This should have a relationship to Capture so that you can link Instance variable to question and other measurements