Measuring youth beliefs about the harms of e-cigarettes and smokeless tobacco compared to cigarettes.

This study examined validity of direct and indirect measures of perceived harm of e-cigarettes and smokeless tobacco (SLT) compared to cigarettes. On direct measures, people compare one product to another, whereas on indirect measures, people rate each product separately and the researcher compares these ratings. Data from youth in Wave 1 of the Population Assessment of Tobacco and Health (PATH) Study (2013-2014) were analyzed (N=13,651 youth aged 12-17years). The study included direct measures of perceived harm of e-cigarettes and SLT compared to cigarettes, and indirect measures were created by comparing ratings of the products. Weighted multinomial logistic regressions tested criterion validity by assessing whether direct and indirect measures were associated with criterion variables, including use of e-cigarettes and SLT. Youth were more likely to rate e-cigarettes as less harmful than cigarettes on the indirect measure (67.3%) than the direct measure (50.2%). The same pattern held for ratings of SLT as less harmful than cigarettes (indirect: 29.7%; direct: 11.7%). Direct measures explained unique variance in product use criterion variables even after adjusting for indirect measures, as did indirect measures after adjusting for direct measures. However, the criterion variables were more often associated with the direct measures than the indirect measures. Results offer preliminary support for using both direct and indirect measures when assessing youth's perceived relative harm of various types of products. However, if researchers cannot include both direct and indirect measures in a study, associations with product use criterion variables support prioritizing direct measures.