Variable Group

A group of variables that may share a common subject, arise from the interpretation of a single question, or are linked by some other factor.

Variable groups are created this way in order to permit variables to belong to multiple groups, including multiple subject groups such as a group of variables on sex and income, or to a subject and a multiple response group, without causing overlapping groups. Variables that are linked by use of the same question need not be identified by a Variable Group element because they are linked by a common unique question identifier in the Variable element. Note that as a result of the strict sequencing required by XML, all Variable Groups must be marked up before the Variable element is opened. That is, the mark-up author cannot mark up a Variable Group, then mark up its constituent variables, then mark up another Variable Group.

The "type" attribute refers to the general type of grouping of the variables, e.g., subject, multiple response. Use the value of "other" if the value is to come from an external controlled vocabulary, and place the term into the otherType attribute.

The "otherType" attribute is used when the "type" attribute has a value of "other". This option should only be used when applying a controlled vocabulary to this attribute. Use the complex element controlledVocabUsed to identify the controlled vocabulary to which the selected term belongs.

Specific variable groups, included within the "type" attribute, are:

Section: Questions which derive from the same section of the questionnaire, e.g., all variables located in Section C.

Multiple response: Questions where the respondent has the opportunity to select more than one answer from a variety of choices, e.g., what newspapers have you read in the past month (with the respondent able to select up to five choices).

Grid: Sub-questions of an introductory or main question but which do not constitute a multiple response group, e.g., I am going to read you some events in the news lately and you tell me for each one whether you are very interested in the event, fairly interested in the fact, or not interested in the event.

Display: Questions which appear on the same interview screen (CAI) together or are presented to the interviewer or respondent as a group.

Repetition: The same variable (or group of variables) which are repeated for different groups of respondents or for the same respondent at a different time.

Subject: Questions which address a common topic or subject, e.g., income, poverty, children.

Version: Variables, often appearing in pairs, which represent different aspects of the same question, e.g., pairs of variables (or groups) which are adjusted/unadjusted for inflation or season or whatever, pairs of variables with/without missing data imputed, and versions of the same basic question.

Iteration: Questions that appear in different sections of the data file measuring a common subject in different ways, e.g., a set of variables which report the progression of respondent income over the life course.

Analysis: Variables combined into the same index, e.g., the components of a calculation, such as the numerator and the denominator of an economic statistic.

Pragmatic: A variable group without shared properties.

Record: Variable from a single record in a hierarchical file.

File: Variable from a single file in a multifile study.

Randomized: Variables generated by CAI surveys produced by one or more random number variables together with a response variable, e.g, random variable X which could equal 1 or 2 (at random) which in turn would control whether Q.23 is worded "men" or "women", e.g., would you favor helping [men/women] laid off from a factory obtain training for a new job?

Other: Variables which do not fit easily into any of the categories listed above, e.g., a group of variables whose documentation is in another language.

The "var" attribute is used to reference all the constituent variable IDs in the group.

The "varGrp" attribute is used to reference all the subsidiary variable groups which nest underneath the current varGrp. This allows for encoding of a hierarchical structure of variable groups.

The attribute "name" provides a name, or short label, for the group.

The "sdatrefs" are summary data description references that record the ID values of all elements within the summary data description section of the Study Description that might apply to the group. These elements include: time period covered, date of collection, nation or country, geographic coverage, geographic unit, unit of analysis, universe, and kind of data.

The "methrefs" are methodology and processing references which record the ID values of all elements within the study methodology and processing section of the Study Description which might apply to the group. These elements include information on data collection and data appraisal (e.g., sampling, sources, weighting, data cleaning, response rates, and sampling error estimates).

The "pubrefs" attribute provides a link to publication/citation references and records the ID values of all citations elements within codeBook/stdyDscr/othrStdyMat or codeBook/otherMat that pertain to this variable group.

The "access" attribute records the ID values of all elements in codeBook/stdyDscr/dataAccs of the document that describe access conditions for this variable group.

The attribute "nCube" was included in 2.0 and subsequent versions in ERROR. DO NOT USE THIS ATTRIBUTE. It is retained only for purposes of backward-compatibility.