What we need done - who will do it?

Vapers need scientific data to support the anecdotal evidence that vaping reduces smoking and/or leads to quitting cigarettes.

I have just read a study that investigated ENDS (Electronic Nicotine Delivery Systems). It has tables, statistics and god-know-what on different aspects exept the one we need - are ENDS successful? Why couldn't they have included that in the study?

"This study represents a snapshot in time of the use of ENDS
from mid-2010 to mid-2011. As the market evolves, awareness,
trial, and use of ENDS is likely to increase. The association
of trial and current use with beliefs about the relative
safety of ENDS highlights the importance of marketing in 
shaping public perceptions around the product. Should regulatory
authorities approve direct claims about reduced
harm, one might expect greater adoption of these products,
at least among current cigarette smokers. If credible evidence
can be provided that ENDS reduces the number of
cigarette smokers and does not attract use among nonsmokers,
then the net public health effect is likely to be positive."

Well - I ask - why didn't this study cover that too?

Who will do it?