The 2006 National Health Interview Survey (NHIS) Paradata File: Overview And Applications

1. The 2006 National Health Interview Survey (NHIS) Paradata File: Overview And Applications Beth L. Taylor 2008 NCHS Data User’s Conference August 13th, 2008

2. 2006 Paradata File Paradata is information about the data collection process Data collected during and immediately after the NHIS interview Part of the NHIS annual data release

3. National Health Interview Survey NHIS – Annual survey of the civilian, non-institutionalized population of the U.S. – sponsored by the National Center for Health Statistics Approximately 35,000 families interviewed annually In-person interview with telephone follow-up allowed 4 ongoing core modules (Household, Family, Sample Child, Sample Adult) plus annual supplements Census Bureau (contractor) carries out field work for Sponsor NCHS

4. Sources of Paradata Contact History Instrument (CHI) - Introduced in 2004 - Produced by the Census Bureau - Used on other Census surveys - Launches each time interviewer accesses the CAPI instrument - Captures data on each visit attempt - In-scope responding and nonresponding households - Out-of-scope households

5. Contact History Instrument Captures whether attempt via phone or personal visit Contact path - Description of contact attempt - Reluctance - Strategies used to complete interviews Noncontact path - Description of attempt - Strategies

6. Contact History Instrument Examples of Strategies: - Advance Letter given - Scheduled appointment - Left note/appointment card - Staked-out household - Checked with neighbors

7. Contact History Instrument CHI data - Family-level file - Summary of contacts, noncontacts, strategies used during interview period - Attempt-level file - Date and time of contact attempt - Description of contact, noncontact, reluctance, strategies used for that visit attempt

8. Sources of NHIS Paradata Front/Back sections of survey instrument - Present on NHIS since late 1990’s - Tailored to NHIS - Language of interview - Cooperativeness of respondent - Mode of interview (personal visit or phone) - Reasons for partial/break-off interviews - Type of noninterview case

9. Sources of NHIS Paradata Time file - Interview times (length of interview start-finish) - Module/Section times (time of 4 core modules and within-module sections) Audit trails - Record of keystrokes - Field times (length of time per question) - Dates - Interviewer notes

10. Paradata File Creation In early 2007 NHIS Paradata Committee established at NCHS to: - Select variables to include on the initial Paradata File release - Weighed issues of confidentiality, usability - Example: Created numerous recodes for CHI file variables

11. Paradata File Release First NHIS Paradata File released in January, 2008 on the Internet (2006 NHIS data) 125 Variables - Family-level file (one record equals one case) Dual uses - Can be analyzed alone or linked to the 2006 health data files

12. Table 1: 2006 Paradata File Frequency Distribution of Cases by Outcome

13. 2006 Paradata File Internet Release: Paradata File Description Document Variable Summary Variable Layout Dataset Sample SAS Input Program Variable Frequencies

14. 2006 Paradata File Release File Description Document - Sample design - Weighting and Variance Estimation - Conceptual grouping of variables - Measures of time, contactability, cooperation - Contact strategies - Partials/Break-offs - Mode measures - Case-level information

15. 2006 Paradata File Release Variable summary - Variable name and brief description of each variable on the file Variable layout - More detailed description - Variable universe - Source (Contact History File, etc.) - Question/Response codes from survey instrument (if applicable) - Notes, recode information

16. 2006 Paradata File Release ASCII dataset (PARADATA.EXE) Sample SAS input program - Formats Variable frequencies

17. Uses of the 2006 Paradata File Stand alone data file (Examples): - The average number of contact attempts it takes to complete the interview - Point in the interview period and time of day when the Sample Adult module was started (Early, Middle, Late) / (Morning, Afternoon, Evening) - Which strategies employed by the interviewer led to successful completion of the interview

18. Uses of the 2006 Paradata File Linked to 2006 health microdata (merge with NHIS Sample Adult File, Family File, etc.) - Item of note: Will not have a 1:1 match with health files because Paradata File has information on nonresponding & out of scope cases - Paradata File has a slightly larger number of interviewed cases than health files - Paradata is field data before cleaning

19. Uses of the 2006 Paradata File Examples of possible research using linked files - Characterizing the characteristics of hard-to-contact families - Modeling the impact of the interview mode on health outcomes

20. Weighting When using the Paradata File as a stand-alone file, use the WTIA_PD variable if making population inferences - This weight reflects the probability of household selection When using the Paradata File to support analyses with the health data files, use the weight variable from the health data file - Example: Use WTFA_SA when merging with the Sample Adult File

21. Variance Estimation NHIS data are obtained through a complex sample design involving stratification, clustering, and multistage sampling - Recommended that users utilize computer software that provides the capability of variance estimation and hypothesis testing for complex sample designs (SUDAAN) - PSU and STRATUM variables included on Paradata File

22. Current NCHS Research Using NHIS Paradata Assessing data quality from the field - Started Quality Assurance Workgroup jointly with Census Bureau to monitor data quality Upcoming presentations

23. Future Steps 2007 Paradata File released in June, 2008 - Nearly identical to 2006 Paradata File release - Telephone items revised for 2007 Expansion for 2008 NHIS Paradata Release - To include data from visit-attempt file, possibly audit trail data (use of function keys, language of interview) Feedback from data users

24. NHIS Paradata File • For more information about the NHIS Paradata File, please visit: http://www.cdc.gov/nchs/about/major/ nhis/2006paradata.htm