Implications of Participant Self-Selection for Generalizability: Who Participates in Smoking Laboratory Research?

Abstract

The generalizability of data from laboratory smoking studies using volunteer samples is debatable. We tracked potential participants from first contact with research staff through screening to study completion. We found that a minority of individuals were ultimately enrolled in the study. Failure to enroll was as often a function of participant lack of attendance at the laboratory as a function of ineligibility. With some exceptions, groups of potential participants were similar regarding demographic characteristics and substance use history. These findings support the generalizability of the sample and highlight the importance of documenting details of study eligibility and participation. The study's limitations are noted.

How generalisable to community samples are clinical trial results for treatment of nicotine dependence: a comparison of common eligibility criteria with respondents of a large representative general population survey

“…Consistent with the existing literature, we found that a lack of motivation to quit and a low level of cigarette consumption explain a large proportion of ineligibility 7 28…”

“…However, they may impair the external validity of the study, since they often exclude a substantial proportion of participants, resulting in a selection bias,5 and extending the gap between research and clinical practice 6. Common exclusion criteria include age, current or past psychiatric/drug disorder, minimal levels of tobacco use and medical conditions 7. There is a risk that this selection of participants affects the results of the treatment trial for nicotine dependence 8 9.…”

“…The impact of eligibility criteria in smoking cessation trials has been discussed in the literature 7 23–29. As called for by CONSORT guidelines, several studies reported the reasons for ineligibility 7 28.…”

“…As called for by CONSORT guidelines, several studies reported the reasons for ineligibility 7 28. For example, Robinson et al screened 1347 adolescents for a nicotine replacement treatment trial, and found that only 24.4% were eligible for inclusion in the trial 28.…”

“…The main reason for ineligibility was a failure to meet minimum requirements regarding the number of cigarettes smoked per day and/or a low level of nicotine dependence (criterion present in 39.1% of ineligible individuals) 28. More recently, Kamholtz et al assessed 97 non-eligible and 201 eligible participants in a laboratory research on smoking 7. They reported that the main reasons for ineligibility were current alcohol and substance use disorders (present in 23.7% and 11.3% of ineligible individuals, respectively) and failure to meet minimum requirement regarding cigarettes smoked per day (24.7%).…”