Appendix B: Quality of the Data

All aspects of survey design and execution affect data quality. This appendix discusses the procedures used to ensure the quality of the data from the 1997 NHSDA and in this Main Findings. Quality control efforts and results in the survey are discussed in terms of respondent cooperation, response rates for the various subsamples, interview and data keying verification, and data editing. Variable recodes, assessment of missing data on key drug use variables, and procedures for dealing with missing data in the analyses are considered where they affect the analytical results and their presentation in the 1997 Main Findings. All phases of survey design, sample selection, data collection, and data preparation were conducted by Research Triangle Institute (RTI).