[Update, 21 May 2015: This paper now appears at International Journal of Environmental Research and Public Health (open access html version here, pdf version downloadable via link). Thanks to readers for the comments on the working paper that improved that version.]
My new working paper is available for download: Phillips – how to detect gateway effects (pdf).
This paper serves multiple purposes. It addresses the titular question, about how an analysis of empirical evidence could support a claim that e-cigarettes, smokeless tobacco, or other low-risk tobacco products are a gateway to smoking. Along the way, it points out that none of the studies to date that are purported to support that claim actually do so. This is also a methods paper (and is being submitted to a methods issue of a journal), and thus goes into some detail on generalizable methodological points. It does so — I believe — in a readable and expository way, such that interested readers can get a lot out of that even if they are not students of epidemiology methods.
This paper is quite different from, but subsumes most of the key content of, my earlier paper that debunks the Glantz et al. claims of finding evidence of a gateway effect. Because the previous paper is somewhat redundant now, I suspect I will not further update it, but will just leave the existing version as an extended appendix of the present paper.
Abstract: Continue reading