Junk study fails to confirm other junk study

There are those who want marijuana legalized and those who don’t – that’s an old story. As we are anti-prohibition, you can imagine our stand.
Today, the war for or against marijuana is fought with trash science salvos – questionnaire-based epidemiological studies, where unverifiable and impossible-to-quantify responses are conjured into exact numbers and then called science.
Recently, and on such a basis, a bunch of urban legends have found a home in junk science. For example, it is suggested that marijuana smoke offers some sort of “protection” from cancer while tobacco smoke “causes” it – yet many of the chemical compounds which result from the burning of either leaf are the same.
The anti-marijuana faction responded to this by rushing to produce a study that “demonstrates” (with questionnaires!) that “marijuana use can increase the risk of psychotic illnesses by 40 percent for casual users and up to 200 percent for heavy users”, and got it published in The Lancet. The pro-marijuana shysters replied with another study (done with questionnaires!) from Johns Hopkins University that “suggest(s) a correlation between the two, but did not find that marijuana was the cause of the increased risk”.
Which version of this witchcraft is right? Who to believe? The general public watches the “battle of the studies” with the impression that a final authority will sort things and offer a final verdict that marijuana is absolutely guaranteed safe, or is simply evil. How can we exist without “public health” revelations in the 21st century, and the apparent certainty they bring?
This is just the tail end of the long junk science saga between those who want pot legalization based on claims about “health” and those who want to keep the substance illegal and also use “health” arguments. Each side pulls out its pet studies, chock full of words like “suggests”, “seems” and “perhaps”, the final conclusion ambivalent and ultimately unhelpful. In the meantime, the same trash science is used to hit alcohol and tobacco in an effort to condition people into believing that abstention is the only way to go.
Of course, the “evidence” of the proselytizers should not be taken seriously. There is only one number that expresses the scientific proofs that they have: zero – a number, by the way, that the “public health” nihilists absolutely love, at least when it appears in the formulation of “zero tolerance”.