back to original question.
What research has been done to show how many heroin users did NOT start with pot.
Thank you for answering on topic.
This research of course would assume that pot is the starting place and would have to find situations where pot was not available but heroin was or any other substance that one things is the starting place. One could just as easily do some research based on any number of assumptions...e.g., heroin use starts with booze, heroin use starts with cigarettes, heroin use starts with anti-drug programs that create fascination about drugs, heroin use starts with bad studies. Assumptions are a poor way to initiate research and one does not prove the null hypothesis.
There are many substances, certainly creating addiction or dependence, that all humans ingest. If all humans ingest them, then all heroin users, being human, have ingested these substances. Perhaps heroin users "start with" aspirin. Perhaps they "start with" sugar.
Where are your studies that beer, or sugar, or aspirin, or antacids, are not the "gateway drugs" that lead to heroin use? Don't their usages predate marijuana use? Perhaps one of them is the real culprit.
Sequence does not lead to correlation, and correlation, as noted, does NOT equal causation. You have to prove that marijuana use leads to heroin use. That is the scientific method.
Anything else is just ideology - ideas accepted as natural fact, but with scientific evidence to prove them.
How is that relevant to anything? I'm sure someone who is a drug user, particularly a hard drug user, would first use a drug that is more mild. It's akin to saying that 99% of all people who rode a roller coaster road a merry-go-round first.