The above argument is convenient for advocates who want to suppress "negative" or "unfavorable" findings by discouraging RCTs - which they believe will "underestimate" the effectiveness of e-cigarettes for smoking cessation and encouraging survey studies - which they believe will show the effects of vapor products in all their possible glory. However, the argument carries with it a lack of scientific validity.

In other words, despite acknowledging that they cannot tell from their study whether e-cigarette use precedes smoking or whether smoking precedes e-cigarette use, they nonetheless draw the conclusion that e-cigarette use precedes smoking.

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