The Semantics of ClassificationMotivating the New Part 2

Jim CarpenterBureau of Labor Statistics

WG2 Meetings Santa Fe, NM January 27-31, 2003

Note on this Presentation

• This presentation focuses on the semantics of “Object X is classified by category Y” and describes the new attributes to record the semantics.

• Other new attributes were discussed in the Open Forum tutorial on Part 2. These attributes are presented in the UML diagrams at the end of this presentation, although they have been updated.

Outline

• The nature of classification

• Meaning of the proposition:– “Object X is classified by category Y”

• Use cases of classification in 11179 MDR

• Attributes of classification schemes that should be in a 11179 MDR

• Proposed model of classification region

Definition of Classification Scheme

the descriptive information for an arrangement or division of objects into groups based on characteristics, which the objects have in common.

– Will use for motivation

• Process of classifying– Dividing objects into groups– MDR should provide descriptive information to

facilitate this process

• Result of classifying– Description information that helps us to understand the

classified item– MDR should provide descriptive information to

understand the statement “object X is classified by the category Y”

Views of Classification“descriptive information for the division of objects into groups”

Following use cases

Fundamental Proposition

• facilitate the classification process

• facilitate understanding the classified item

The MDR should provide the attributes that:

Example of Classification• Scheme for classifying writing instruments

• Writing instrument: an object used for making marks on some material

• Differentiating characteristic: material in the writing instrument that makes the mark

• Material Name of category– chalk chalk– ink pen– lead pencil

• “Object X is classified as a pen” has meaning

Meaning• “Object X is classified as a pen” is equivalent to• “Object X is a writing instrument that uses ink to

make marks”– We naturally substitute the category label with the

description of the category– Just like a concise terminological definition

• Experiment– If I give you a funny looking object and tell you it is a

pen, you know more about it if you know about “pen”. – If you don’t know, then the classification scheme

provides the descriptive information

Object X is classified as a “pen”

• Object X is a subtype of the class pen.

• But not all classifications are subtype relationships

Question

• What is the meaning of:

Data element X is classified by the category of “pen” ?

• Answer: Data element X is associated in some way with objects that are pens.

Data element X is classified by the category of “pen”

• Data element identifier: xxx• Data element name: Pen Ink Color• Context: office supply database• Object class: pen• Property: color of ink• Data element concept: ink color for a pen

• Data element xxx has a data element concept with the object class “pen”

Data Element

Pen

Pen DEC-Object Class DE relationship

has DEC with the object class of type

is object class in DEC for

Use Case Setting

– Objects to classify: data elements– Characteristic used to classify: the day of the

week in which an object was created– Category names: Monday, Tuesday, Wednesday,

Thursday, Friday, Saturday, Sunday– Category type description:

• day of the week in which an event occurred

Classify data elements according to the day of the week in which they were created.

Common Semantics

• Day of the week is a time interval

• A time interval describes an event (occurrence)

Use Case Setting, cont.

• Data element - Identifier : 111

• Data element - Creation date: Monday, January 27, 2003

Classification Scheme 1• Classification Scheme – Identifier : 0001• Classification Scheme – Name : Days of the week • Classification Scheme – Type name : List • Category – Values : Mon, Tue, Wed, Thu, Fri, Sat,

Sun • Category – Type name : abbreviation for the name

of a day of the week (when an event occurred)• Result : the proposition “data element 111 is

classified by the Category with value = Sun” “D.E. 111 is associated with an event that

happened on a Sunday”

Use Case 1:

Missing Information

• Known by the classifier:– Data element creation date

• “Data element 111 was created on a Wednesday.”

• “was created on” is an attribute of the classification relationship– to be supplied by the classifier

Use Case of current MDR model:

Conclusion 1

• The classification relationship in ISO 11179 needs an attribute

• The attribute should describe the characteristic of the administered item used by the classifier

Classification_RelationshipDiscription

Categorytype_name [0..1] : String

Administered_Itemadministration_record [1..1] : Administration_Record

0..*

0..*

classifying0..*

classified_by

0..*

Classification Scheme 2• Classification Scheme – Identifier : 0002

• Classification Scheme – Name : Days of the week

• Classification Scheme – Type name : List

• Category – Values : 1, 2, 3, 4, 5, 6, 7

• Category – Type name : Numerical designation for a day of the week (when an event occurred)

• Result : the proposition “data element 111 is classified by the Category with value = 7, which represents a day of the week”

Use Case 2:

Missing Information

• Attribute value of the classification relationship– Creation date

• Meaning of the value 7– Which day of the week is 7?– Could be provided by a reference document

• Inconvenient

• Not machine readable

Conclusion 2

• Need an attribute of Category that states the meaning of the Category value

Complex Categories

• Complexity from users viewpoint– Multiple characteristics– Fuzzy boundaries– Technical terms– Numerous types and instances of category

relationships

Conclusion 3

Users need more than concise terminological definitions of categories– Included concepts– Excluded concepts– Examples– Illustrations (picture, sound, animation, …)

Non-English Language Speaking User

• All information is missing

• Need translations of attribute values

Conclusion 4

• Designations and definitions of terms should be represented in the languages of the MDR users

Proposed Model Summary of Changes

• Make category an administered item

• Expand Terminological Entry class– Signs – language independent– More definitional types

• Make classification relation an administered item

• Other useful attributes

Note: The following diagrams use inheritanceas discussed this morning. Administration_Recordis removed as an attribute from all Administered_Itemtypes

Data Element

Object Class Property

Value DomainConceptual Domain

Data Element Concept

Administered Itemadministration_record [1..1] : Administration_Record

Classification Scheme Category

Context

Administered_Itemadministration_record [1..1] : Administration_Record

Context

Sign

Terminological Entry

Predicate Statement

Designation Definition

Excluded Concept

Example

Included Concept

Language Section

Term Section

Note

Category_Relationshiptype_description [1..1] : Stringfacet [0..1] : String

Classification_Relationship

Classification_Schemesource_artifact_type [0..1] : Artifact_Typestructure_type [1..1] : C_S_Structure_Typenotation_system [0..n] : Notation_Systemvariance_estimate_reference [0..n] : Reference Document

Categorytype_name [0..1] : String

1..*

0..*

containing

1..*

contained in

0..* 0..*

0..*

0..*

0..*

Administered_Itemadministration_record [1..1] : Administration_Record

0..*

0..*

classify0..*

classified_by0..*