1. Organizing Groups Why, When and How to do it

2. Brief history of the need for groups In the old days of MARC records you could either be a machine readable file OR you could be a series…but not both We all knew that some data sets were more closely aligned than others but we weren’t allowed to say so DDI carried on this tradition by focusing on the codebook

3. Need for change Multiple files could be processed using the same codebook Some data collection processes were designed to be a series  Longitudinal series  Time series  Waves Sometimes multiple files were “integrated” in order to make a single file described by a single code book

4. Why Group? Identifies study units that were intended to be analyzed together Provides comparative information for accurate linking where appropriate Allows for easier reuse of information and less redundancy Provides new discovery, analysis, and management options

5. When does grouping occur? Whenever it wants to Predetermined grouping patterns  Occurs once the second study unit for the group is being prepared  Standards can be moved into Group and used by subsequent modules Post-facto grouping  Full instances exist already  Comparative information is the primary concern

6. How to group Determine the criteria for the group Identify common items for “standards”  Concepts [note that comparability is based on the description NOT the label]  Questions  Variable/categories Fill out the grid

7. The Grid Time  Single or multiple  Regular or Irregular occurrence  Continuing or limited duration Instrument  Single or multiple Panel Geography Data Sets produced (integrated etc.)

8. Single Occurrenc e ? Regularly Occurring Continuing Survey yes no yes no yes no yes no TIME VALUE EXPECTED INFORMATION In GROUPLower in Model [in Data Collection] T1Single Data Date Range T2Periodicity Start Date Single Date Date Range T3Periodicity Date Range Single Date Date Range T4Description of occurrence model Start Date Single Date Date Range T5Description of occurrence model Date Range Single Date Date Range

9. Single Instrument ? Linked set of instruments covering different topics or populations Core with Topical Modules yes no yes INSTRUMENTS VALUE EXPECTED INFORMATION In GROUPLower in Model [in Data Collection] I1Instrument specific information I2Number of instruments Relationship of Instruments Linking mechanism Relationship between instrument and panel(s) Instrument specific information I3Variance in periodicity of core and topic modules Relationship between instrument and panel(s) Instrument specific information

10. Repeated Survey no yes no yes no PANEL Single Panel ? VALUE EXPECTED INFORMATION In GROUPLower in Model [in Data Collection and not covered in other attribute information] G1Number of repeats for panel Universe G2Universe Sampling method and size G3Overall Universe Wave pattern Number of repeats per panel Specific Universes Specifics in sampling method and size G4Overall Universe Sample selection/ differentiation Specific Universe Specifics in sampling method and size

11. Repeated Survey no yes no yes no GEOGRAPHY Single Geographic Area ? VALUE EXPECTED INFORMATION In GROUPLower in Model [in Data Collection and not covered in other attribute information] G1Number of repeats for geography Geographic Cover G2Geographic Cover G3Overall Geographic Cover Wave pattern Number of repeats per geography Specific Geographic Cover G4Overall Geographic Cover Geographic selection/ differentiation Specific Geographic Cover Changes in geographic selection

12. Single dataset no yes no yes no LOGICAL DATASET Single data collection activity ? VALUE EXPECTED INFORMATION In GROUPLower in Model [in Data Collection or lower and not covered in other attribute information] D1 D2Rational for multiple logical products Product mix details Specific logical data set information [in logical data descriptions with links back to questionnaire]; possible concept keys [logical module} D3Integration basis Purpose of integration Selection process Linking process Harmonization process Specifics of individual data collection processes D4Dataset to data collection activity mapping