RTI International is a trade name of Research Triangle Institute

1. Panel Survey of Hospitals: Sampling and Estimation Challenges Darryl V. Creel Third International Conference on Establishment Surveys Montreal, Quebec, Canada June 18-21, 2007 RTI International is a trade name of Research Triangle Institute 6110 Executive Blvd. ■ Suite 902 ■ Rockville, Maryland, USA 27709 Phone 301-770-8229 e-mail dcreel@rti.org

2. Outline • Purpose of Survey • Survey Design • Frame Development • Substitution • Estimation

3. Purpose of the Survey • Level of Drug Use and Abuse • Monitor Drug Use and Abuse Changes over Time

4. Survey Design • Complete Survey Redesign (New Beginning 2004) • Start of a New Panel – Maximize Overlap with Previous Panel • Change in Stratification Scheme • Geography • Ownership • Size • Stratified SRS WOR of Hospitals • Review All Emergency Department Visits • Change in Case Eligibility • Annual Sample Updates to Account for New Hospitals • Change in Contractors

5. Survey Design • Possible Modification to the New Design • Could Not Review All Emergency Department Visits in Some Hospitals • Added a Second Stage of Sampling to the New Design • Select Days within Month to Review Emergency Department Visits for Eligible Cases • Retain Single-stage Design • Standard Errors – Worst Case Single-Stage SE 97% of Two-Stage SE • Computational Time – Single-Stage ~ 300 Observations Took 12 Minutes, Two-Stage ~ 70,000 Observations Took 31.5 Hours

6. Frame Development • American Hospital Association (AHA) Annual Survey Database • Good Coverage • Inaccuracies in the File • Incorrect FIPS Information Some for Counties in FL • Nonexistant Codes • Inaccuracies in the Documentation • Counts for Changes in the Population not Consistent • Only Use a Few Variables from AHA • Stratification • Eligibility Determination

7. Frame Development • Changes in Populations of Statistical Units (Struijs and Willeboordse) • Change of Characteristics • Change of Existence • Birth • Death • Change of Structure • Concentration • Merger • Takeover • Deconcentration • Break-Up • Split-Off • Restructuring • Track for Allocation Emergency Department Visits Counts

8. Substitution • Hospitals are Difficult to Recruit • Use Responding Not Sampled Hospitals from the Previous Panel for Nonresponding Sampled Hospitals in Current Panel until Number of Nonresponding Hospitals in Current Panel Decreases • Substitution Only Occurs within a Sampling Stratum, i.e., Same Geography, Ownership Category, and Size Category • Match Number of Emergency Department Visits as Closely as Possible

9. Estimation • Main Focus on Analysis of Trends • Drug Classification Scheme Changes Constantly • Apply Most Recent Classification Scheme Retrospectively for Trends

10. Estimation • Actual Zero Eligible Cases • Some Hospitals Not on Micro-data Set, i.e., No Eligible Cases Found at Hospital During Charts Review • Hospitals on Micro-data Set May Not Have Specific Drugs, e.g., PCP • Carries Through to Specific Analysis • Generate Data with a Zero Value • Statistician Involvement Across All Aspects of the Survey • SUDAAN – SAMPCNT Statement

11. Summary • Purpose of Survey • Survey Design • Frame Development • Substitution • Estimation • Statisticians Involved