These were minimized for this survey by a pre-testing conducted at Indiana University, specialized training of people who administered the survey, coding checks when completed questionnaires were scanned, and checks of quality control. Where the survey team suspects nonsampling errors, these have been noted in this report. In other words, the reported current use of a particular drug may vary slightly from one sample to the next, because of the natural differences which exist in people, their location, social practices, etc. For example, people in the far southern end of the state may have slightly different use rates of particular drugs than people in the extreme northwest corner of the state, and the state-wide results may not reflect an accurate picture of the drug use rates throughout the state if disproportionate numbers of people are sampled in the south relative to the northwest portion of the state. These errors were minimized by allocating the number of sites in each of the 10 geographic regions used by the Governor's Commission for A Drug-Free Indiana and by setting a minimum of 50 respondents and a maximum of 2,500 respondents at each site.
Scientists use statistical formulas to calculate an estimate of the amount of sampling error.
Hundreds of such estimates would have to be made for this report, based upon the exact number of responses in each cell category. To avoid unnecessary difficulty in reading such reports, it is customary to report the average estimate of sampling error, recognizing that the error may be larger in cells with very small numbers of respondents. Participation in all three surveys was strictly voluntary. Over time, additional reports will be issued using the data collected in this survey.