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Improving self-reports of drug-use: numeric estimates as fuzzy sets

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This study compared traditional crisp set to fuzzy set representations of quantitative estimates of drug use to investigate what survey respondents recall about their drug use. Design 

Sample survey comparing (a) responses to traditional survey questions asking for single numeric estimates to (b) responses to fuzzy set questions asking for boundary estimates of drug use. Setting 

Research facilities of a public university in a large southern California city. Participants 

Community residents using tobacco, alcohol, marijuana or amphetamine (n = 88). Measurements 

Personal interviews in which participants reported onset, frequency and daily rate of tobacco, alcohol, marijuana and amphetamine use based on traditional survey questions and fuzzy set questions. Findings 

With the exception of marijuana use, fuzzy boundary estimates differed significantly from the traditional point estimates (P < 0.05). Median retest reliabilities for fuzzy boundary estimates were 0.96 (tobacco), 0.81 (alcohol), 0.96 (marijuana) and 0.95 (amphetamine). The degree of vagueness varied by behavior and drug, with estimates of daily rates showing greatest fuzziness and onset of use showing least fuzziness. Conclusions 

Participants recall more about past drug use than a single numeric estimate. All numeric estimates of drug use showed fuzzy set properties. Compared to traditional self-reports of drug use, fuzzy set representations provide a more complete and detailed description of what participants recall about past drug use.
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Keywords: Drug use; fuzzy set reliability; self-reports; validity

Document Type: Research Article

Affiliations: 1: Department of Psychology, 2: and SDSU/UCSD Joint Doctoral Program in Clinical Psychology, San Diego State University, CA, USA

Publication date: 01 September 2003

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