Logical Product Module

 DDI
Version 3_0
Target ddi:logicalproduct:3_0
Schema File logicalproduct.xsd

Description

The Logical Product module provides information on the intellectual content and structure of a data file. It consists of a category scheme made up of categories and the grouping of those categories in specific response structures, variables that use those category groups in specified ways, and/or aggregate data NCubes assembled from those variables. The relationships between variables and questions, variables and concepts, and variables and the processing used to create them are indicated through referencing. Concepts are noted in the Study Unit and referenced by the variable and NCube. Questions are noted in the Data Collection module and referenced by variables. The advantage of this approach is that one can identify which variables from the multiple logical products of a study were derived from the same questions. In addition, one can store the data in any data storage format and know that the contents of the data file refer to the same variable. The general constructs are as follows:

Schema overview

import reusable.xsd ddi:reusable:3_0
simpleType AdditivityCodeType -
element AggregationDefinition -
complexType AggregationDefinitionType Identifies the independent (denominator) and dependent (numerator) dimensions for calculating aggregate measures such as percent. When two or more independent or dependent dimensions are listed here, the value is defined as the intersection of the listed dimensions.
simpleType AggregationMethodCodeType A list for describing aggregation methods.
element AttachmentGroupReference References the coordinate group to which the attribute attaches.
element AttachmentLevel Identifies attachment level of attribute
simpleType AttachmentLevelCodeType -
element Attribute Defines a variable that describes an attribute of all or coordinate sections of the NCube.
complexType AttributeType Defines a variable that describes an attribute of all or coordinate sections of the NCube.
element BaseLogicalProduct -
complexType BaseLogicalProductType -
element CaseIdentification There may be more than one means of identifying a record. For example a US Census Summary File has a LogicalRecordIdentifer that is unique to the original file within which it was published. A specific geography has a set of fields that identify it uniquely.
complexType CaseIdentificationType Describes the information needed to identify an individual case within a record type.
element CaseSpecification Value of variable indicating this record type, multiple entries allow for multiple valid values or ranges.
complexType CaseSpecificationType Value of variable indicating this record type, multiple entries allow for multiple valid values or ranges.
element Category A description of a particular category or response. OECD Glossary of Statistical Terms: Generic term for items at any level within a classification, typically tabulation categories, sections, subsections, divisions, subdivisions, groups, subgroups, classes and subclasses.
element CategoryGroup Allows for grouping of categories.
complexType CategoryGroupType Allows for grouping of categories.
element CategoryReference Provides the specific category of the variable included.
element CategoryScheme Contains descriptions of particular categories used as question responses and in the logical product. Their relationships and code values are described in the code scheme.
element CategorySchemeReference Reference to a previously defined category scheme either internal to or external to the xml instance.
complexType CategorySchemeType -
complexType CategoryType A description of a particular category or response. OECD Glossary of Statistical Terms: Generic term for items at any level within a classification, typically tabulation categories, sections, subsections, divisions, subdivisions, groups, subgroups, classes and subclasses.
element Code Reference to included category is found in the ReferenceType. This standard type is extended by the CodeType which allows for additional information regarding the category as well as nesting of codes.
element CodeRepresentation Defines the representation of a variable as a set or subset of codes from a code scheme.
complexType CodeRepresentationType Describes a coded representation.
element CodeScheme Provides a description of a set of categories that have a specific relationship, such as the categories Male and Female that can be grouped together as Gender. Categories (e.g., Male and Female) can belong to multiple code schemes. The code scheme also provides the unique code values for each of the categories in the code scheme.
element CodeSchemeReference References a code scheme, or part of a code scheme.
complexType CodeSchemeReferenceType Describes a coded representation.
complexType CodeSchemeType Describes the structure of a Code Scheme.
group CodeSubsetInfo -
complexType CodeType -
element CodingInstructionsReference Any special instructions that were provided to those who converted information from one form to another to derive a particular variable. This might include the reordering of numeric information into another form or the conversion of textual information into numeric information. The specifics of this process are provided in the data collection module element Coding, which is referenced here.
complexType CohortType Defines a dimension and its value.
element ComponentReference Reference to variable or category used for the derivation.
element ConcatenatedValue Provides a reference to another variable and describes the method for deriving the value of this variable by concatenating a collection of other variables. This is useful in creating concatenated keys.
complexType ConcatenatedValueType Describes the variables whose concatenated values make up the existing concatenated variable.
element ConceptReference General concept to which this variable belongs. The concept itself is found in the studyunit module. Reference to a concept may either be made directly through this element or via a reference to a question that is linked to a concept.
element CoordinateGroup Defines groups of dimensions (given particular values) to which attributes can be attached.
complexType CoordinateGroupType Defines groups of dimensions (given particular values) to which attributes can be attached.
complexType DataExisitenceType Allows for inclusion of upper level categories that will not have associated data. In this case they act as the DDI version 2 form of category group.
element DataExistence Allows for inclusion of upper level categories that will not have associated data. In this case they act as the DDI version 2 form of category group.
element DataRelationship Contains a written description of how the logical contents of the file relate to each other for programming purposes. For example, noting that there are household, family and person items where the household is identified by variableH the unique family by the concatenation of variableH and variableF and the unique person within a household by the concatenation of variableH and variableP.
complexType DataRelationshipType Describes the relationships among logical records in the dataset. Date Relationship is needed to create the appropriate link between the logical record and the physical storage description. Data Relationship is optional because a logical product can contain only a category scheme and/or code scheme.
element DateTimeRepresentation Defines the representation of a varaible as a date or time value.
element Definition Definition of the category. Note that comparison of categories is determined by the Definition rather than the Label. For example, while the Definition of a Chemist in London and a Pharmacist in New York is the same and comparable, the definitions of Chemist in each location differ significantly and are NOT comparable
element Dimension Defines a variable as a dimension of the nCube, and should be repeated to describe each of the nCube's dimensions.
complexType DimensionType -
element DimensionValue Defines a variable as a dimension of the coordinate group.
element EmbargoReference Reference to embargo information pertaining to this variable.
element ExternalCategoryRepresentation Structures a response domain based on a categorization that is external to DDI, for example, a category list for occupations or geography.
element Generation Generation/derivation details of the category.
complexType GenerationType Generation/derivation details of the category.
element GroupType A generic element for specifying a reason for a variable or nCube group. Note that this element can contain either a term from a controlled vocabulary list or a textual description.
element GroupTypeCoded A suggested controlled vocabulary of group types.
complexType GroupTypeCodedType A suggested enumeration of group types. Indicates reasons for grouping.
simpleType HierarchyCodeType -
element HierarchyType Identifies the type of hierarchy used in the nesting of categories within the code scheme. Possible values are Regular and Irregular. A regular nesting indicates that the category hierarchy is consistent to the lowest levels of the hierarchy, i.e. the lowest levels of the hierarchy are at the same level for every branch on the hierarchy.
element ImputationReference Reference to the imputation process described in the Data Processing section
element IncludedCodeReference Allows selection of code schemes to use not based on levels.
complexType IncludedCodeReferenceType Allows selection of specific codes not based on levels.
element Interval Identifies the interval between each value of the categories for this variable. Used only for categories with interval relationship
complexType IntervalType Describes the structure, starting point and increment step of an interval.
simpleType IsComprehensiveType Indicates values of the isComprehensive attribute.
element Level Used to describe the levels of the code scheme hierarchy. The level describes the nesting structure of a hierarchical coding structure. The use of Level relates back to the inclusion of descriptions for nested categories in version 2.1. Levels take the place of category groups as they were used in DDI versions through 2.1. Category groups in version 2.1 became upper category levels in hierarchical descriptions in version 3. A level could have data attached to it (summary of its children) or no data attached to it (the equivalent of creating a category group in 2.0 and earlier versions Note that the attribute levelNumber is used for referencing specific codes to their level identifier.
complexType LevelType Used to describe the levels of the code scheme hierarchy. The level describes the nesting structure of a hierarchical coding structure. A level could have data attached to it (summary of its children) or no data attached to it (the equivalent of creating a category group in 2.0 and earlier versions Note that the attribute levelNumber is used for referencing specific codes to their level identifier.
element LogicalProduct -
complexType LogicalProductType Describes the logical content of standard variables.
element LogicalRecord A logical record such as a household, family, or person record.
complexType LogicalRecordType Describes the logical record in terms of identification of its type, case identification, its relationship with other records, and support for multiple storage segments. Required to link a description of a physical record structure to its logical record.
element Measure The measurement features of the cell content (repeatable only for regularly bundled arrays of cell content).
complexType MeasureType -
element NCube Describes and NCube.
element NCubeGroup Describes a group of NCubes.
element NCubeGroupReference Constituent variable group. This allows for nesting of variable groups.
complexType NCubeGroupType Describes a group of NCubes.
element NCubeLogicalProduct -
complexType NCubeLogicalProductType Describes the logical structure of NCubes.
element NCubeReference Constituent variable.
element NCubeScheme Contains a collection of NCubes and NCube groups.
element NCubeSchemeReference -
complexType NCubeSchemeType -
complexType NCubeType Describes the structure of the NCube.
element NCubesInRecord Lists the NCubes contained in the record.
complexType NCubesInRecordType Lists the NCubes contained in the record.
element NumericRepresentation Defines the representation of a varaible as a number, number range, or sequence, or set interval of numbers.
element Purpose Purpose for which the nCube was created.
element QuestionReference Reference to question(s) used to collect data for this variable. The question is found in the datacollection module.
element Range Indicates that the Cube contains only a limited number of categories from the code scheme.
complexType RangeType -
element RecordReferenceSource Reference to the Source Record.
complexType RecordReferenceSourceType Reference to the Source Record.
element RecordReferenceTarget Reference to the Target Record.
element RecordRelationship All relationships are pairwise. Multiple pairwise relationships maybe needed to clarify all relationships within a logical product.
complexType RecordRelationshipType All relationships are described pairwise. Multiple pairwise relationships may be needed to clarify all relationships within a logical product.
simpleType RelationCodeType Indicates relation.
element RelationshipType Code describing the relationship between categories of the level. Possible values are either Nominal, Ordinal, or Interval. Note that different levels may have different values within the same hierarchy. For example Level 1 items may be ordinal and Level 2 (the children of Level 1 items) may be nominal.
element Representation Describes the representation of the variable, including categories, data typing, and computation information.
complexType RepresentationType Type to describe the representation of a variable
element StandardWeightReference Reference to a standard weight, as described in the DataCollection module.
element SupportForMultipleSegments Information concerning support for breaking the logical record into segments for storage purposes. Some files may be broken into record segments for storage but lack variables to support identification of specific segments. In this case segments are identified by their physical order within the storage file.
element TextRepresentation Defines the representation of a varaible as a text field. This field can be restricted to a length.
element Value Value of variable indicating this record type.
element ValueRepresentation Substitution group head for describing the representation value of the variable.
complexType ValueType Type for indicating value of variable
simpleType ValueTypeCodeType Indicates value type.
element Variable Describes a variable contained in the variable scheme.
element VariableConcatenation Describes the concatenation of other variables, based on a category value of this variable that can be used to identify or locate a specific record of this type. Used to identify unique identification string for a record of a specific category type. For example: A summary level indicating a state record may only require a STATE code to identify it in addition to its summary level category value, while a COUNTY would require a specific summary level value plus a STATE code and a COUNTY code.
complexType VariableConcatenationType Describes the structure of the concatenated variable.
element VariableDefinition Additional textual descriptions of the variable.
element VariableGroup Describes a variable group contained in the variable scheme.
element VariableGroupReference References a variable group contained in the variable scheme.
complexType VariableGroupType Contains a group of variables, which may be hierarchical.
element VariableReference References a variable contained in the variable scheme.
element VariableScheme Contains a collection of variables and variable groups.
element VariableSchemeReference References a variable scheme for inclusion in another variable scheme.
complexType VariableSchemeType -
element VariableSpecificationReference Repetition allows multi-variable specifications of unique value.
complexType VariableSpecificationReferenceType Describes the information needed to identify a type of record. Repeating the field will allow referencing multiple variables.
complexType VariableType Describes the structure of a Variable.
element VariableUsedReference A variable reference which can indicate either inclusion or exclusion from the referenced scheme for each variable.
complexType VariableUsedReferenceType -
element VariableValueReference Reference to the variable containing the record type locator.
complexType VariableValueReferenceType Describes the variable containing the record type locator and the value being used.
element VariablesInRecord List of all variables used in record either directly or as found in a defined VariableGroup; note that a variable can be used in multiple records.
complexType VariablesInRecordType Identifies the variables in the record type.
element WeightVariableReference Reference to weight variable(s) to be used with this variable.