Fig 1.
Tree diagram of the unrelated question method (UQM).
p denotes the probability of receiving the sensitive question; πn denotes the probability of answering the neutral question with “yes”; πs denotes the prevalence for the sensitive question.
Table 1.
Explanation of the different questionnaire versions.
Table 2.
Distribution of the different questionnaire versions.
Table 3.
Characteristics of the respondents.
Table 4.
Estimated 12-month prevalences for physical and cognitive doping using the UQM for p ≈ 1/3 and p ≈ 2/3*.