Unfortunately the findings are flawed. From page 8:
"Theoretically, the vaporizer might have been expected to realize a
higher THC delivery efficiency than combustion, since it should have
avoided loss of THC by pyrolysis. That this was not observed indicates
that there were other inefficiencies in the vaporization process. The
most likely explanation would seem to be incomplete vaporization, due
to lack of uniform thorough heating and ventilation of the sample.
It is
certainly possible that higher efficiencies might have been achieved by
stirring the sample and drawing another balloon from the vaporizer, as
recommended by the manufacturer."
They're saying that if they would have used the Volcano according to the manufacture's instructions, the results would have been different. No kidding. As anyone can attest to, using a vaporizer takes some time to figure out the best delivery method. Some doods in a lab using a Volcano three times does not make for a good data to go on.
But I digress, it's pretty well established that when combusting material, some of the cannabinoids are destroyed in the process. Vaporaization allows for extraction of many of those cannabinoids without destroying them. The key is to start with low temperatures and work your way up. This way you're extracting the whole spectrum of cannabinoids. And ABV that you're left with can be used for all sorts of edibles, extracting even MORE cannabinoids still.
Vaporizing is a complete win/win when it comes to extracting the most cannabinoids versus combusting.