Physical and cognitive doping in university students using the unrelated question model

Study objectives A short paper-and-pencil questionnaire was distributed to 1.243 university students assessing the 12-month prevalence of physical and cognitive doping using two versions of the UQM with different probabilities for receiving the sensitive question (p [almost equal to] 1/3 and p [almost equal to] 2/3). Likelihood ratio tests were used to assess whether the prevalence estimates for physical and cognitive doping differed significantly between p [almost equal to] 1/3 and p [almost equal to] 2/3. The order of questions (physical doping and cognitive doping) as well as the probability of receiving the sensitive question (p [almost equal to] 1/3 or p [almost equal to] 2/3) were counterbalanced across participants. Statistical power analyses were performed to determine sample size. The prevalence estimate for physical doping with p [almost equal to] 1/3 was 22.5% (95% CI: 10.8-34.1), and 12.8% (95% CI: 7.6-18.0) with p [almost equal to] 2/3. For cognitive doping with p [almost equal to] 1/3, the estimated prevalence was 22.5% (95% CI: 11.0-34.1), whereas it was 18.0% (95% CI: 12.5-23.5) with p [almost equal to] 2/3. Likelihood-ratio tests revealed that prevalence estimates for both physical and cognitive doping, respectively, did not differ significantly under p [almost equal to] 1/3 and p [almost equal to] 2/3 (physical doping: X.sup.2 = 2.25, df = 1, p = 0.13; cognitive doping: X.sup.2 = 0.49, df = 1, p = 0.48). Bayes factors computed with the Savage-Dickey method favored the null ("the prevalence estimates are identical under p [almost equal to] 1/3 and p [almost equal to] 2/3") over the alternative ("the prevalence estimates differ under p [almost equal to] 1/3 and p [almost equal to] 2/3") hypothesis for both physical doping (BF = 2.3) and cognitive doping (BF = 5.3). The present results suggest that prevalence estimates for physical and cognitive doping assessed by the UQM are largely unaffected by the probability for receiving the sensitive question p.