A second major advantage of a clinical trial is that it can examine the potential effectiveness of interventions in which the use of a product is promoted for use among smokers who are interested in quitting. A survey cannot do this, because it can only examine the use of products under current conditions. It provides no information on what would happen if the product was actively promoted to a group of smokers, as it is in a clinical trial.

The biggest problem with Stan's approach is that when you examine e-cigarette users who are not using the product to quit, you are introducing a huge sampling bias. For example, why might someone use e-cigarettes, but not to quit? Most likely, the majority of vapers who are using e-cigarettes for a purpose other than cessation are using e-cigarettes to cut down on the amount they smoke. They are likely to derive benefits from smoking reduction. However, they are almost assuredly not going to quit smoking because they are not trying to quit, nor do they have such a desire.

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