Seems misleading. "Marijuana users excluded and added to Marijuana smokers group". Would have been fruitful if there were 4 groups, Marijuana only, Mixed, Tob

Seems misleading. "Marijuana users excluded and added to Marijuana smokers group". Would have been fruitful if there were 4 groups, Marijuana only, Mixed, Tobacco only, and Non-Smokers. The introduction seems kinda biased from the start: "Marijuana is the most widely used illicit psychoactive substance in the world (1) and the second-most commonly smoked substance after tobacco..." "...Its use has increased in Canada since the legalization of Medical...". does not compute.